media/src/main/java/android/support/v4/media/session/MediaControllerCompat.java - platform/frameworks/support - Git at Google

 /*
  * Copyright 2018 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package android.support.v4.media.session;

 import static androidx.annotation.RestrictTo.Scope.LIBRARY;
 import static androidx.annotation.RestrictTo.Scope.LIBRARY_GROUP_PREFIX;

 import android.app.Activity;
 import android.app.PendingIntent;
 import android.content.Context;
 import android.media.AudioManager;
 import android.media.MediaMetadata;
 import android.media.Rating;
 import android.media.session.MediaController;
 import android.media.session.MediaSession;
 import android.media.session.PlaybackState;
 import android.net.Uri;
 import android.os.Build;
 import android.os.Bundle;
 import android.os.Handler;
 import android.os.IBinder;
 import android.os.Looper;
 import android.os.Message;
 import android.os.RemoteException;
 import android.os.ResultReceiver;
 import android.support.v4.media.MediaBrowserCompat;
 import android.support.v4.media.MediaDescriptionCompat;
 import android.support.v4.media.MediaMetadataCompat;
 import android.support.v4.media.RatingCompat;
 import android.support.v4.media.session.MediaSessionCompat.QueueItem;
 import android.support.v4.media.session.PlaybackStateCompat.CustomAction;
 import android.text.TextUtils;
 import android.util.Log;
 import android.view.KeyEvent;

 import androidx.annotation.GuardedBy;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.annotation.RequiresApi;
 import androidx.annotation.RestrictTo;
 import androidx.core.app.BundleCompat;
 import androidx.core.app.ComponentActivity;
 import androidx.media.AudioAttributesCompat;
 import androidx.media.VolumeProviderCompat;
 import androidx.versionedparcelable.ParcelUtils;
 import androidx.versionedparcelable.VersionedParcelable;

 import java.lang.ref.WeakReference;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.concurrent.ConcurrentHashMap;

 /**
  * Allows an app to interact with an ongoing media session. Media buttons and
  * other commands can be sent to the session. A callback may be registered to
  * receive updates from the session, such as metadata and play state changes.
  * <p>
  * A MediaController can be created if you have a {@link MediaSessionCompat.Token}
  * from the session owner.
  * <p>
  * MediaController objects are thread-safe.
  * <p>
  * This is a helper for accessing features in {@link android.media.session.MediaSession}
  * introduced after API level 4 in a backwards compatible fashion.
  * <p class="note">
  * If MediaControllerCompat is created with a {@link MediaSessionCompat.Token session token}
  * from another process, following methods will not work directly after the creation if the
  * {@link MediaSessionCompat.Token session token} is not passed through a
  * {@link MediaBrowserCompat}:
  * <ul>
  * <li>{@link #getPlaybackState()}.{@link PlaybackStateCompat#getExtras() getExtras()}</li>
  * <li>{@link #getRatingType()}</li>
  * <li>{@link #getRepeatMode()}</li>
  * <li>{@link #getSessionInfo()}</li>
  * <li>{@link #getShuffleMode()}</li>
  * <li>{@link #isCaptioningEnabled()}</li>
  * </ul></p>
  *
  * <div class="special reference">
  * <h3>Developer Guides</h3>
  * <p>For information about building your media application, read the
  * <a href="{@docRoot}guide/topics/media-apps/index.html">Media Apps</a> developer guide.</p>
  * </div>
  */
 public final class MediaControllerCompat {
     static final String TAG = "MediaControllerCompat";

     /**
      * @hide
      */
     @RestrictTo(LIBRARY)
     public static final String COMMAND_GET_EXTRA_BINDER =
             "android.support.v4.media.session.command.GET_EXTRA_BINDER";
     /**
      * @hide
      */
     @RestrictTo(LIBRARY)
     public static final String COMMAND_ADD_QUEUE_ITEM =
             "android.support.v4.media.session.command.ADD_QUEUE_ITEM";
     /**
      * @hide
      */
     @RestrictTo(LIBRARY)
     public static final String COMMAND_ADD_QUEUE_ITEM_AT =
             "android.support.v4.media.session.command.ADD_QUEUE_ITEM_AT";
     /**
      * @hide
      */
     @RestrictTo(LIBRARY)
     public static final String COMMAND_REMOVE_QUEUE_ITEM =
             "android.support.v4.media.session.command.REMOVE_QUEUE_ITEM";
     /**
      * @hide
      */
     @RestrictTo(LIBRARY)
     public static final String COMMAND_REMOVE_QUEUE_ITEM_AT =
             "android.support.v4.media.session.command.REMOVE_QUEUE_ITEM_AT";

     /**
      * @hide
      */
     @RestrictTo(LIBRARY)
     public static final String COMMAND_ARGUMENT_MEDIA_DESCRIPTION =
             "android.support.v4.media.session.command.ARGUMENT_MEDIA_DESCRIPTION";
     /**
      * @hide
      */
     @RestrictTo(LIBRARY)
     public static final String COMMAND_ARGUMENT_INDEX =
             "android.support.v4.media.session.command.ARGUMENT_INDEX";

     private static class MediaControllerExtraData extends ComponentActivity.ExtraData {
         private final MediaControllerCompat mMediaController;

         MediaControllerExtraData(MediaControllerCompat mediaController) {
             mMediaController = mediaController;
         }

         MediaControllerCompat getMediaController() {
             return mMediaController;
         }
     }

     /**
      * Sets a {@link MediaControllerCompat} in the {@code activity} for later retrieval via
      * {@link #getMediaController(Activity)}.
      *
      * <p>This is compatible with {@link Activity#setMediaController(MediaController)}.
      * If {@code activity} inherits {@link androidx.fragment.app.FragmentActivity}, the
      * {@code mediaController} will be saved in the {@code activity}. In addition to that,
      * on API 21 and later, {@link Activity#setMediaController(MediaController)} will be
      * called.</p>
      *
      * @param activity The activity to set the {@code mediaController} in, must not be null.
      * @param mediaController The controller for the session which should receive
      *     media keys and volume changes on API 21 and later.
      * @see #getMediaController(Activity)
      * @see Activity#setMediaController(android.media.session.MediaController)
      */
     public static void setMediaController(@NonNull Activity activity,
             MediaControllerCompat mediaController) {
         if (activity instanceof ComponentActivity) {
             ((ComponentActivity) activity).putExtraData(
                     new MediaControllerExtraData(mediaController));
         }
         if (android.os.Build.VERSION.SDK_INT >= 21) {
             MediaController controllerFwk = null;
             if (mediaController != null) {
                 Object sessionTokenObj = mediaController.getSessionToken().getToken();
                 controllerFwk = new MediaController(activity, (MediaSession.Token) sessionTokenObj);
             }
             activity.setMediaController(controllerFwk);
         }
     }

     /**
      * Retrieves the {@link MediaControllerCompat} set in the activity by
      * {@link #setMediaController(Activity, MediaControllerCompat)} for sending media key and volume
      * events.
      *
      * <p>This is compatible with {@link Activity#getMediaController()}.</p>
      *
      * @param activity The activity to get the media controller from, must not be null.
      * @return The controller which should receive events.
      * @see #setMediaController(Activity, MediaControllerCompat)
      */
     public static MediaControllerCompat getMediaController(@NonNull Activity activity) {
         if (activity instanceof ComponentActivity) {
             MediaControllerExtraData extraData =
                     ((ComponentActivity) activity).getExtraData(MediaControllerExtraData.class);
             return extraData != null ? extraData.getMediaController() : null;
         } else if (android.os.Build.VERSION.SDK_INT >= 21) {
             MediaController controllerFwk = activity.getMediaController();
             if (controllerFwk == null) {
                 return null;
             }
             MediaSession.Token sessionTokenFwk = controllerFwk.getSessionToken();
             try {
                 return new MediaControllerCompat(activity,
                         MediaSessionCompat.Token.fromToken(sessionTokenFwk));
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in getMediaController.", e);
             }
         }
         return null;
     }

     @SuppressWarnings("WeakerAccess") /* synthetic access */
     static void validateCustomAction(String action, Bundle args) {
         if (action == null) {
             return;
         }
         switch(action) {
             case MediaSessionCompat.ACTION_FOLLOW:
             case MediaSessionCompat.ACTION_UNFOLLOW:
                 if (args == null
                         || !args.containsKey(MediaSessionCompat.ARGUMENT_MEDIA_ATTRIBUTE)) {
                     throw new IllegalArgumentException("An extra field "
                             + MediaSessionCompat.ARGUMENT_MEDIA_ATTRIBUTE + " is required "
                             + "for this action " + action + ".");
                 }
                 break;
         }
     }

     private final MediaControllerImpl mImpl;
     private final MediaSessionCompat.Token mToken;
     // This set is used to keep references to registered callbacks to prevent them being GCed,
     // since we only keep weak references for callbacks in this class and its inner classes.
     // It is actually a map not a set. Ignore the values and treat the keys as a set.
     private final ConcurrentHashMap<Callback, Boolean> mRegisteredCallbacks =
             new ConcurrentHashMap<>();

     /**
      * Creates a media controller from a session.
      *
      * @param session The session to be controlled.
      */
     public MediaControllerCompat(Context context, @NonNull MediaSessionCompat session) {
         if (session == null) {
             throw new IllegalArgumentException("session must not be null");
         }
         mToken = session.getSessionToken();

         MediaControllerImpl impl = null;
         try {
             if (android.os.Build.VERSION.SDK_INT >= 21) {
                 impl = new MediaControllerImplApi21(context, mToken);
             } else {
                 impl = new MediaControllerImplBase(mToken);
             }
         } catch (RemoteException e) {
             Log.w(TAG, "Failed to create MediaControllerImpl.", e);
         }
         mImpl = impl;
     }

     /**
      * Creates a media controller from a session token which may have
      * been obtained from another process.
      *
      * @param sessionToken The token of the session to be controlled.
      * @throws RemoteException if the session is not accessible.
      */
     public MediaControllerCompat(Context context, @NonNull MediaSessionCompat.Token sessionToken)
             throws RemoteException {
         if (sessionToken == null) {
             throw new IllegalArgumentException("sessionToken must not be null");
         }
         mToken = sessionToken;

         if (android.os.Build.VERSION.SDK_INT >= 21) {
             mImpl = new MediaControllerImplApi21(context, sessionToken);
         } else {
             mImpl = new MediaControllerImplBase(sessionToken);
         }
     }

     /**
      * Gets a {@link TransportControls} instance for this session.
      *
      * @return A controls instance
      */
     public TransportControls getTransportControls() {
         return mImpl.getTransportControls();
     }

     /**
      * Sends the specified media button event to the session. Only media keys can
      * be sent by this method, other keys will be ignored.
      *
      * @param keyEvent The media button event to dispatch.
      * @return true if the event was sent to the session, false otherwise.
      */
     public boolean dispatchMediaButtonEvent(KeyEvent keyEvent) {
         if (keyEvent == null) {
             throw new IllegalArgumentException("KeyEvent may not be null");
         }
         return mImpl.dispatchMediaButtonEvent(keyEvent);
     }

     /**
      * Gets the current playback state for this session.
      *
      * <p>If the session is not ready, {@link PlaybackStateCompat#getExtras()} on the result of
      * this method may return null. </p>
      *
      * @return The current PlaybackState or null
      * @see #isSessionReady
      * @see Callback#onSessionReady
      */
     public PlaybackStateCompat getPlaybackState() {
         return mImpl.getPlaybackState();
     }

     /**
      * Gets the current metadata for this session.
      *
      * @return The current MediaMetadata or null.
      */
     public MediaMetadataCompat getMetadata() {
         return mImpl.getMetadata();
     }

     /**
      * Gets the current play queue for this session if one is set. If you only
      * care about the current item {@link #getMetadata()} should be used.
      *
      * @return The current play queue or null.
      */
     public List<QueueItem> getQueue() {
         return mImpl.getQueue();
     }

     /**
      * Adds a queue item from the given {@code description} at the end of the play queue
      * of this session. Not all sessions may support this. To know whether the session supports
      * this, get the session's flags with {@link #getFlags()} and check that the flag
      * {@link MediaSessionCompat#FLAG_HANDLES_QUEUE_COMMANDS} is set.
      *
      * @param description The {@link MediaDescriptionCompat} for creating the
      *            {@link MediaSessionCompat.QueueItem} to be inserted.
      * @throws UnsupportedOperationException If this session doesn't support this.
      * @see #getFlags()
      * @see MediaSessionCompat#FLAG_HANDLES_QUEUE_COMMANDS
      */
     public void addQueueItem(MediaDescriptionCompat description) {
         mImpl.addQueueItem(description);
     }

     /**
      * Adds a queue item from the given {@code description} at the specified position
      * in the play queue of this session. Shifts the queue item currently at that position
      * (if any) and any subsequent queue items to the right (adds one to their indices).
      * Not all sessions may support this. To know whether the session supports this,
      * get the session's flags with {@link #getFlags()} and check that the flag
      * {@link MediaSessionCompat#FLAG_HANDLES_QUEUE_COMMANDS} is set.
      *
      * @param description The {@link MediaDescriptionCompat} for creating the
      *            {@link MediaSessionCompat.QueueItem} to be inserted.
      * @param index The index at which the created {@link MediaSessionCompat.QueueItem}
      *            is to be inserted.
      * @throws UnsupportedOperationException If this session doesn't support this.
      * @see #getFlags()
      * @see MediaSessionCompat#FLAG_HANDLES_QUEUE_COMMANDS
      */
     public void addQueueItem(MediaDescriptionCompat description, int index) {
         mImpl.addQueueItem(description, index);
     }

     /**
      * Removes the first occurrence of the specified {@link MediaSessionCompat.QueueItem}
      * with the given {@link MediaDescriptionCompat description} in the play queue of the
      * associated session. Not all sessions may support this. To know whether the session supports
      * this, get the session's flags with {@link #getFlags()} and check that the flag
      * {@link MediaSessionCompat#FLAG_HANDLES_QUEUE_COMMANDS} is set.
      *
      * @param description The {@link MediaDescriptionCompat} for denoting the
      *            {@link MediaSessionCompat.QueueItem} to be removed.
      * @throws UnsupportedOperationException If this session doesn't support this.
      * @see #getFlags()
      * @see MediaSessionCompat#FLAG_HANDLES_QUEUE_COMMANDS
      */
     public void removeQueueItem(MediaDescriptionCompat description) {
         mImpl.removeQueueItem(description);
     }

     /**
      * Removes an queue item at the specified position in the play queue
      * of this session. Not all sessions may support this. To know whether the session supports
      * this, get the session's flags with {@link #getFlags()} and check that the flag
      * {@link MediaSessionCompat#FLAG_HANDLES_QUEUE_COMMANDS} is set.
      *
      * @param index The index of the element to be removed.
      * @throws UnsupportedOperationException If this session doesn't support this.
      * @see #getFlags()
      * @see MediaSessionCompat#FLAG_HANDLES_QUEUE_COMMANDS
      * @deprecated Use {@link #removeQueueItem(MediaDescriptionCompat)} instead.
      */
     @Deprecated
     public void removeQueueItemAt(int index) {
         List<QueueItem> queue = getQueue();
         if (queue != null && index >= 0 && index < queue.size()) {
             QueueItem item = queue.get(index);
             if (item != null) {
                 removeQueueItem(item.getDescription());
             }
         }
     }

     /**
      * Gets the queue title for this session.
      */
     public CharSequence getQueueTitle() {
         return mImpl.getQueueTitle();
     }

     /**
      * Gets the extras for this session.
      */
     public Bundle getExtras() {
         return mImpl.getExtras();
     }

     /**
      * Gets the rating type supported by the session. One of:
      * <ul>
      * <li>{@link RatingCompat#RATING_NONE}</li>
      * <li>{@link RatingCompat#RATING_HEART}</li>
      * <li>{@link RatingCompat#RATING_THUMB_UP_DOWN}</li>
      * <li>{@link RatingCompat#RATING_3_STARS}</li>
      * <li>{@link RatingCompat#RATING_4_STARS}</li>
      * <li>{@link RatingCompat#RATING_5_STARS}</li>
      * <li>{@link RatingCompat#RATING_PERCENTAGE}</li>
      * </ul>
      * <p>If the session is not ready, it will return {@link RatingCompat#RATING_NONE}.</p>
      *
      * @return The supported rating type, or {@link RatingCompat#RATING_NONE} if the value is not
      *         set or the session is not ready.
      * @see #isSessionReady
      * @see Callback#onSessionReady
      */
     public int getRatingType() {
         return mImpl.getRatingType();
     }

     /**
      * Returns whether captioning is enabled for this session.
      *
      * <p>If the session is not ready, it will return a {@code false}.</p>
      *
      * @return {@code true} if captioning is enabled, {@code false} if disabled or not set.
      * @see #isSessionReady
      * @see Callback#onSessionReady
      */
     public boolean isCaptioningEnabled() {
         return mImpl.isCaptioningEnabled();
     }

     /**
      * Gets the repeat mode for this session.
      *
      * @return The latest repeat mode set to the session,
      *         {@link PlaybackStateCompat#REPEAT_MODE_NONE} if not set, or
      *         {@link PlaybackStateCompat#REPEAT_MODE_INVALID} if the session is not ready yet.
      * @see #isSessionReady
      * @see Callback#onSessionReady
      */
     public int getRepeatMode() {
         return mImpl.getRepeatMode();
     }

     /**
      * Gets the shuffle mode for this session.
      *
      * @return The latest shuffle mode set to the session, or
      *         {@link PlaybackStateCompat#SHUFFLE_MODE_NONE} if disabled or not set, or
      *         {@link PlaybackStateCompat#SHUFFLE_MODE_INVALID} if the session is not ready yet.
      * @see #isSessionReady
      * @see Callback#onSessionReady
      */
     public int getShuffleMode() {
         return mImpl.getShuffleMode();
     }

     /**
      * Gets the flags for this session. Flags are defined in
      * {@link MediaSessionCompat}.
      *
      * @return The current set of flags for the session.
      */
     public long getFlags() {
         return mImpl.getFlags();
     }

     /**
      * Gets the current playback info for this session.
      *
      * @return The current playback info or null.
      */
     public PlaybackInfo getPlaybackInfo() {
         return mImpl.getPlaybackInfo();
     }

     /**
      * Gets an intent for launching UI associated with this session if one
      * exists.
      *
      * @return A {@link PendingIntent} to launch UI or null.
      */
     public PendingIntent getSessionActivity() {
         return mImpl.getSessionActivity();
     }

     /**
      * Gets the token for the session that this controller is connected to.
      *
      * @return The session's token.
      */
     public MediaSessionCompat.Token getSessionToken() {
         return mToken;
     }

     /**
      * Gets the SessionToken in media2 as VersionedParcelable for the session that this controller
      * is connected to.
      *
      * @return The session's token as VersionedParcelable.
      * @hide
      */
     @RestrictTo(LIBRARY_GROUP_PREFIX)
     public @Nullable VersionedParcelable getSession2Token() {
         return mToken.getSession2Token();
     }

     /**
      * Sets the volume of the output this session is playing on. The command will
      * be ignored if it does not support
      * {@link VolumeProviderCompat#VOLUME_CONTROL_ABSOLUTE}. The flags in
      * {@link AudioManager} may be used to affect the handling.
      *
      * @see #getPlaybackInfo()
      * @param value The value to set it to, between 0 and the reported max.
      * @param flags Flags from {@link AudioManager} to include with the volume
      *            request.
      */
     public void setVolumeTo(int value, int flags) {
         mImpl.setVolumeTo(value, flags);
     }

     /**
      * Adjusts the volume of the output this session is playing on. The direction
      * must be one of {@link AudioManager#ADJUST_LOWER},
      * {@link AudioManager#ADJUST_RAISE}, or {@link AudioManager#ADJUST_SAME}.
      * The command will be ignored if the session does not support
      * {@link VolumeProviderCompat#VOLUME_CONTROL_RELATIVE} or
      * {@link VolumeProviderCompat#VOLUME_CONTROL_ABSOLUTE}. The flags in
      * {@link AudioManager} may be used to affect the handling.
      *
      * @see #getPlaybackInfo()
      * @param direction The direction to adjust the volume in.
      * @param flags Any flags to pass with the command.
      */
     public void adjustVolume(int direction, int flags) {
         mImpl.adjustVolume(direction, flags);
     }

     /**
      * Adds a callback to receive updates from the Session. Updates will be
      * posted on the caller's thread.
      *
      * @param callback The callback object, must not be null.
      */
     public void registerCallback(@NonNull Callback callback) {
         registerCallback(callback, null);
     }

     /**
      * Adds a callback to receive updates from the session. Updates will be
      * posted on the specified handler's thread.
      *
      * @param callback The callback object, must not be null.
      * @param handler The handler to post updates on. If null the callers thread
      *            will be used.
      */
     public void registerCallback(@NonNull Callback callback, Handler handler) {
         if (callback == null) {
             throw new IllegalArgumentException("callback must not be null");
         }
         if (mRegisteredCallbacks.putIfAbsent(callback, true) != null) {
             Log.w(TAG, "the callback has already been registered");
             return;
         }
         if (handler == null) {
             handler = new Handler();
         }
         callback.setHandler(handler);
         mImpl.registerCallback(callback, handler);
     }

     /**
      * Stops receiving updates on the specified callback. If an update has
      * already been posted you may still receive it after calling this method.
      *
      * @param callback The callback to remove
      */
     public void unregisterCallback(@NonNull Callback callback) {
         if (callback == null) {
             throw new IllegalArgumentException("callback must not be null");
         }
         if (mRegisteredCallbacks.remove(callback) == null) {
             Log.w(TAG, "the callback has never been registered");
             return;
         }
         try {
             mImpl.unregisterCallback(callback);
         } finally {
             callback.setHandler(null);
         }
     }

     /**
      * Sends a generic command to the session. It is up to the session creator
      * to decide what commands and parameters they will support. As such,
      * commands should only be sent to sessions that the controller owns.
      *
      * @param command The command to send
      * @param params Any parameters to include with the command. Can be {@code null}.
      * @param cb The callback to receive the result on. Can be {@code null}.
      */
     public void sendCommand(@NonNull String command, @Nullable Bundle params,
             @Nullable ResultReceiver cb) {
         if (TextUtils.isEmpty(command)) {
             throw new IllegalArgumentException("command must neither be null nor empty");
         }
         mImpl.sendCommand(command, params, cb);
     }

     /**
      * Returns whether the session is ready or not.
      *
      * <p>If the session is not ready, following methods can work incorrectly.</p>
      * <ul>
      * <li>{@link #getPlaybackState()}</li>
      * <li>{@link #getRatingType()}</li>
      * <li>{@link #getRepeatMode()}</li>
      * <li>{@link #getSessionInfo()}}</li>
      * <li>{@link #getShuffleMode()}</li>
      * <li>{@link #isCaptioningEnabled()}</li>
      * </ul>
      *
      * @return true if the session is ready, false otherwise.
      * @see Callback#onSessionReady()
      */
     public boolean isSessionReady() {
         return mImpl.isSessionReady();
     }

     /**
      * Gets the session owner's package name.
      *
      * @return The package name of of the session owner.
      */
     public String getPackageName() {
         return mImpl.getPackageName();
     }

     /**
      * Gets the additional session information which was set when the session was created.
      * The returned {@link Bundle} can include additional unchanging information about the session.
      * For example, it can include the version of the session application, or other app-specific
      * unchanging information.
      *
      * @return The additional session information, or {@link Bundle#EMPTY} if the session
      *         didn't set the information or if the session is not ready.
      * @see #isSessionReady
      * @see Callback#onSessionReady
      */
     @NonNull
     public Bundle getSessionInfo() {
         return mImpl.getSessionInfo();
     }

     /**
      * Gets the underlying framework
      * {@link android.media.session.MediaController} object.
      * <p>
      * This method is only supported on API 21+.
      * </p>
      *
      * @return The underlying {@link android.media.session.MediaController}
      *         object, or null if none.
      */
     public Object getMediaController() {
         return mImpl.getMediaController();
     }

     /**
      * Callback for receiving updates on from the session. A Callback can be
      * registered using {@link #registerCallback}
      */
     public static abstract class Callback implements IBinder.DeathRecipient {
         final MediaController.Callback mCallbackFwk;
         MessageHandler mHandler;
         IMediaControllerCallback mIControllerCallback;

         public Callback() {
             if (android.os.Build.VERSION.SDK_INT >= 21) {
                 mCallbackFwk = new MediaControllerCallbackApi21(this);
             } else {
                 mCallbackFwk = null;
                 mIControllerCallback = new StubCompat(this);
             }
         }

         /**
          * Override to handle the session being ready.
          *
          * @see MediaControllerCompat#isSessionReady
          */
         public void onSessionReady() {
         }

         /**
          * Override to handle the session being destroyed. The session is no
          * longer valid after this call and calls to it will be ignored.
          */
         public void onSessionDestroyed() {
         }

         /**
          * Override to handle custom events sent by the session owner without a
          * specified interface. Controllers should only handle these for
          * sessions they own.
          *
          * @param event The event from the session.
          * @param extras Optional parameters for the event.
          */
         public void onSessionEvent(String event, Bundle extras) {
         }

         /**
          * Override to handle changes in playback state.
          *
          * @param state The new playback state of the session
          */
         public void onPlaybackStateChanged(PlaybackStateCompat state) {
         }

         /**
          * Override to handle changes to the current metadata.
          *
          * @param metadata The current metadata for the session or null if none.
          * @see MediaMetadataCompat
          */
         public void onMetadataChanged(MediaMetadataCompat metadata) {
         }

         /**
          * Override to handle changes to items in the queue.
          *
          * @see MediaSessionCompat.QueueItem
          * @param queue A list of items in the current play queue. It should
          *            include the currently playing item as well as previous and
          *            upcoming items if applicable.
          */
         public void onQueueChanged(List<QueueItem> queue) {
         }

         /**
          * Override to handle changes to the queue title.
          *
          * @param title The title that should be displayed along with the play
          *            queue such as "Now Playing". May be null if there is no
          *            such title.
          */
         public void onQueueTitleChanged(CharSequence title) {
         }

         /**
          * Override to handle changes to the {@link MediaSessionCompat} extras.
          *
          * @param extras The extras that can include other information
          *            associated with the {@link MediaSessionCompat}.
          */
         public void onExtrasChanged(Bundle extras) {
         }

         /**
          * Override to handle changes to the audio info.
          *
          * @param info The current audio info for this session.
          */
         public void onAudioInfoChanged(PlaybackInfo info) {
         }

         /**
          * Override to handle changes to the captioning enabled status.
          *
          * @param enabled {@code true} if captioning is enabled, {@code false} otherwise.
          */
         public void onCaptioningEnabledChanged(boolean enabled) {
         }

         /**
          * Override to handle changes to the repeat mode.
          *
          * @param repeatMode The repeat mode. It should be one of followings:
          *                   {@link PlaybackStateCompat#REPEAT_MODE_NONE},
          *                   {@link PlaybackStateCompat#REPEAT_MODE_ONE},
          *                   {@link PlaybackStateCompat#REPEAT_MODE_ALL},
          *                   {@link PlaybackStateCompat#REPEAT_MODE_GROUP}
          */
         public void onRepeatModeChanged(@PlaybackStateCompat.RepeatMode int repeatMode) {
         }

         /**
          * Override to handle changes to the shuffle mode.
          *
          * @param shuffleMode The shuffle mode. Must be one of the followings:
          *                    {@link PlaybackStateCompat#SHUFFLE_MODE_NONE},
          *                    {@link PlaybackStateCompat#SHUFFLE_MODE_ALL},
          *                    {@link PlaybackStateCompat#SHUFFLE_MODE_GROUP}
          */
         public void onShuffleModeChanged(@PlaybackStateCompat.ShuffleMode int shuffleMode) {
         }

         /**
          * @hide
          */
         @RestrictTo(LIBRARY_GROUP_PREFIX)
         public IMediaControllerCallback getIControllerCallback() {
             return mIControllerCallback;
         }

         @Override
         public void binderDied() {
             postToHandler(MessageHandler.MSG_DESTROYED, null, null);
         }

         /**
          * Set the handler to use for callbacks.
          */
         void setHandler(Handler handler) {
             if (handler == null) {
                 if (mHandler != null) {
                     mHandler.mRegistered = false;
                     mHandler.removeCallbacksAndMessages(null);
                     mHandler = null;
                 }
             } else {
                 mHandler = new MessageHandler(handler.getLooper());
                 mHandler.mRegistered = true;
             }
         }

         void postToHandler(int what, Object obj, Bundle data) {
             if (mHandler != null) {
                 Message msg = mHandler.obtainMessage(what, obj);
                 msg.setData(data);
                 msg.sendToTarget();
             }
         }

         // Callback methods in this class are run on handler which was given to registerCallback().
         @RequiresApi(21)
         private static class MediaControllerCallbackApi21 extends MediaController.Callback {
             private final WeakReference<MediaControllerCompat.Callback> mCallback;

             MediaControllerCallbackApi21(MediaControllerCompat.Callback callback) {
                 mCallback = new WeakReference<>(callback);
             }

             @Override
             public void onSessionDestroyed() {
                 MediaControllerCompat.Callback callback = mCallback.get();
                 if (callback != null) {
                     callback.onSessionDestroyed();
                 }
             }

             @Override
             public void onSessionEvent(String event, Bundle extras) {
                 MediaSessionCompat.ensureClassLoader(extras);
                 MediaControllerCompat.Callback callback = mCallback.get();
                 if (callback != null) {
                     if (callback.mIControllerCallback != null
                             && android.os.Build.VERSION.SDK_INT < 23) {
                         // Ignore. ExtraCallback will handle this.
                     } else {
                         callback.onSessionEvent(event, extras);
                     }
                 }
             }

             @Override
             public void onPlaybackStateChanged(PlaybackState stateObj) {
                 MediaControllerCompat.Callback callback = mCallback.get();
                 if (callback != null) {
                     if (callback.mIControllerCallback != null) {
                         // Ignore. ExtraCallback will handle this.
                     } else {
                         callback.onPlaybackStateChanged(
                                 PlaybackStateCompat.fromPlaybackState(stateObj));
                     }
                 }
             }

             @Override
             public void onMetadataChanged(MediaMetadata metadataObj) {
                 MediaControllerCompat.Callback callback = mCallback.get();
                 if (callback != null) {
                     callback.onMetadataChanged(MediaMetadataCompat.fromMediaMetadata(metadataObj));
                 }
             }

             @Override
             public void onQueueChanged(List<MediaSession.QueueItem> queue) {
                 MediaControllerCompat.Callback callback = mCallback.get();
                 if (callback != null) {
                     callback.onQueueChanged(QueueItem.fromQueueItemList(queue));
                 }
             }

             @Override
             public void onQueueTitleChanged(CharSequence title) {
                 MediaControllerCompat.Callback callback = mCallback.get();
                 if (callback != null) {
                     callback.onQueueTitleChanged(title);
                 }
             }

             @Override
             public void onExtrasChanged(Bundle extras) {
                 MediaSessionCompat.ensureClassLoader(extras);
                 MediaControllerCompat.Callback callback = mCallback.get();
                 if (callback != null) {
                     callback.onExtrasChanged(extras);
                 }
             }

             @Override
             public void onAudioInfoChanged(MediaController.PlaybackInfo info) {
                 MediaControllerCompat.Callback callback = mCallback.get();
                 if (callback != null) {
                     callback.onAudioInfoChanged(new PlaybackInfo(
                             info.getPlaybackType(),
                             AudioAttributesCompat.wrap(info.getAudioAttributes()),
                             info.getVolumeControl(),
                             info.getMaxVolume(),
                             info.getCurrentVolume()));
                 }
             }
         }

         private static class StubCompat extends IMediaControllerCallback.Stub {
             private final WeakReference<MediaControllerCompat.Callback> mCallback;

             StubCompat(MediaControllerCompat.Callback callback) {
                 mCallback = new WeakReference<>(callback);
             }

             @Override
             public void onEvent(String event, Bundle extras) throws RemoteException {
                 MediaControllerCompat.Callback callback = mCallback.get();
                 if (callback != null) {
                     callback.postToHandler(MessageHandler.MSG_EVENT, event, extras);
                 }
             }

             @Override
             public void onSessionDestroyed() throws RemoteException {
                 MediaControllerCompat.Callback callback = mCallback.get();
                 if (callback != null) {
                     callback.postToHandler(MessageHandler.MSG_DESTROYED, null, null);
                 }
             }

             @Override
             public void onPlaybackStateChanged(PlaybackStateCompat state) throws RemoteException {
                 MediaControllerCompat.Callback callback = mCallback.get();
                 if (callback != null) {
                     callback.postToHandler(MessageHandler.MSG_UPDATE_PLAYBACK_STATE, state, null);
                 }
             }

             @Override
             public void onMetadataChanged(MediaMetadataCompat metadata) throws RemoteException {
                 MediaControllerCompat.Callback callback = mCallback.get();
                 if (callback != null) {
                     callback.postToHandler(MessageHandler.MSG_UPDATE_METADATA, metadata, null);
                 }
             }

             @Override
             public void onQueueChanged(List<QueueItem> queue) throws RemoteException {
                 MediaControllerCompat.Callback callback = mCallback.get();
                 if (callback != null) {
                     callback.postToHandler(MessageHandler.MSG_UPDATE_QUEUE, queue, null);
                 }
             }

             @Override
             public void onQueueTitleChanged(CharSequence title) throws RemoteException {
                 MediaControllerCompat.Callback callback = mCallback.get();
                 if (callback != null) {
                     callback.postToHandler(MessageHandler.MSG_UPDATE_QUEUE_TITLE, title, null);
                 }
             }

             @Override
             public void onCaptioningEnabledChanged(boolean enabled) throws RemoteException {
                 MediaControllerCompat.Callback callback = mCallback.get();
                 if (callback != null) {
                     callback.postToHandler(
                             MessageHandler.MSG_UPDATE_CAPTIONING_ENABLED, enabled, null);
                 }
             }

             @Override
             public void onRepeatModeChanged(int repeatMode) throws RemoteException {
                 MediaControllerCompat.Callback callback = mCallback.get();
                 if (callback != null) {
                     callback.postToHandler(MessageHandler.MSG_UPDATE_REPEAT_MODE, repeatMode, null);
                 }
             }

             @Override
             public void onShuffleModeChangedRemoved(boolean enabled) throws RemoteException {
                 // Do nothing.
             }

             @Override
             public void onShuffleModeChanged(int shuffleMode) throws RemoteException {
                 MediaControllerCompat.Callback callback = mCallback.get();
                 if (callback != null) {
                     callback.postToHandler(
                             MessageHandler.MSG_UPDATE_SHUFFLE_MODE, shuffleMode, null);
                 }
             }

             @Override
             public void onExtrasChanged(Bundle extras) throws RemoteException {
                 MediaControllerCompat.Callback callback = mCallback.get();
                 if (callback != null) {
                     callback.postToHandler(MessageHandler.MSG_UPDATE_EXTRAS, extras, null);
                 }
             }

             @Override
             public void onVolumeInfoChanged(ParcelableVolumeInfo info) throws RemoteException {
                 MediaControllerCompat.Callback callback = mCallback.get();
                 if (callback != null) {
                     PlaybackInfo pi = null;
                     if (info != null) {
                         pi = new PlaybackInfo(info.volumeType, info.audioStream, info.controlType,
                                 info.maxVolume, info.currentVolume);
                     }
                     callback.postToHandler(MessageHandler.MSG_UPDATE_VOLUME, pi, null);
                 }
             }

             @Override
             public void onSessionReady() throws RemoteException {
                 MediaControllerCompat.Callback callback = mCallback.get();
                 if (callback != null) {
                     callback.postToHandler(MessageHandler.MSG_SESSION_READY, null, null);
                 }
             }
         }

         private class MessageHandler extends Handler {
             private static final int MSG_EVENT = 1;
             private static final int MSG_UPDATE_PLAYBACK_STATE = 2;
             private static final int MSG_UPDATE_METADATA = 3;
             private static final int MSG_UPDATE_VOLUME = 4;
             private static final int MSG_UPDATE_QUEUE = 5;
             private static final int MSG_UPDATE_QUEUE_TITLE = 6;
             private static final int MSG_UPDATE_EXTRAS = 7;
             private static final int MSG_DESTROYED = 8;
             private static final int MSG_UPDATE_REPEAT_MODE = 9;
             private static final int MSG_UPDATE_CAPTIONING_ENABLED = 11;
             private static final int MSG_UPDATE_SHUFFLE_MODE = 12;
             private static final int MSG_SESSION_READY = 13;

             boolean mRegistered = false;

             MessageHandler(Looper looper) {
                 super(looper);
             }

             @Override
             @SuppressWarnings("unchecked")
             public void handleMessage(Message msg) {
                 if (!mRegistered) {
                     return;
                 }
                 switch (msg.what) {
                     case MSG_EVENT: {
                         Bundle extras = msg.getData();
                         MediaSessionCompat.ensureClassLoader(extras);
                         onSessionEvent((String) msg.obj, extras);
                         break;
                     }
                     case MSG_UPDATE_PLAYBACK_STATE:
                         onPlaybackStateChanged((PlaybackStateCompat) msg.obj);
                         break;
                     case MSG_UPDATE_METADATA:
                         onMetadataChanged((MediaMetadataCompat) msg.obj);
                         break;
                     case MSG_UPDATE_QUEUE:
                         onQueueChanged((List<QueueItem>) msg.obj);
                         break;
                     case MSG_UPDATE_QUEUE_TITLE:
                         onQueueTitleChanged((CharSequence) msg.obj);
                         break;
                     case MSG_UPDATE_CAPTIONING_ENABLED:
                         onCaptioningEnabledChanged((boolean) msg.obj);
                         break;
                     case MSG_UPDATE_REPEAT_MODE:
                         onRepeatModeChanged((int) msg.obj);
                         break;
                     case MSG_UPDATE_SHUFFLE_MODE:
                         onShuffleModeChanged((int) msg.obj);
                         break;
                     case MSG_UPDATE_EXTRAS: {
                         Bundle extras = (Bundle) msg.obj;
                         MediaSessionCompat.ensureClassLoader(extras);
                         onExtrasChanged(extras);
                         break;
                     }
                     case MSG_UPDATE_VOLUME:
                         onAudioInfoChanged((PlaybackInfo) msg.obj);
                         break;
                     case MSG_DESTROYED:
                         onSessionDestroyed();
                         break;
                     case MSG_SESSION_READY:
                         onSessionReady();
                         break;
                 }
             }
         }
     }

     /**
      * Interface for controlling media playback on a session. This allows an app
      * to send media transport commands to the session.
      */
     public static abstract class TransportControls {
         /**
          * Used as an integer extra field in {@link #playFromMediaId(String, Bundle)} or
          * {@link #prepareFromMediaId(String, Bundle)} to indicate the stream type to be used by the
          * media player when playing or preparing the specified media id. See {@link AudioManager}
          * for a list of stream types.
          */
         public static final String EXTRA_LEGACY_STREAM_TYPE =
                 "android.media.session.extra.LEGACY_STREAM_TYPE";

         TransportControls() {
         }

         /**
          * Request that the player prepare for playback. This can decrease the time it takes to
          * start playback when a play command is received. Preparation is not required. You can
          * call {@link #play} without calling this method beforehand.
          */
         public abstract void prepare();

         /**
          * Request that the player prepare playback for a specific media id. This can decrease the
          * time it takes to start playback when a play command is received. Preparation is not
          * required. You can call {@link #playFromMediaId} without calling this method beforehand.
          *
          * @param mediaId The id of the requested media.
          * @param extras Optional extras that can include extra information about the media item
          *               to be prepared.
          */
         public abstract void prepareFromMediaId(String mediaId, Bundle extras);

         /**
          * Request that the player prepare playback for a specific search query. This can decrease
          * the time it takes to start playback when a play command is received. An empty or null
          * query should be treated as a request to prepare any music. Preparation is not required.
          * You can call {@link #playFromSearch} without calling this method beforehand.
          *
          * @param query The search query.
          * @param extras Optional extras that can include extra information
          *               about the query.
          */
         public abstract void prepareFromSearch(String query, Bundle extras);

         /**
          * Request that the player prepare playback for a specific {@link Uri}. This can decrease
          * the time it takes to start playback when a play command is received. Preparation is not
          * required. You can call {@link #playFromUri} without calling this method beforehand.
          *
          * @param uri The URI of the requested media.
          * @param extras Optional extras that can include extra information about the media item
          *               to be prepared.
          */
         public abstract void prepareFromUri(Uri uri, Bundle extras);

         /**
          * Request that the player start its playback at its current position.
          */
         public abstract void play();

         /**
          * Request that the player start playback for a specific {@link Uri}.
          *
          * @param mediaId The uri of the requested media.
          * @param extras Optional extras that can include extra information
          *            about the media item to be played.
          */
         public abstract void playFromMediaId(String mediaId, Bundle extras);

         /**
          * Request that the player start playback for a specific search query.
          * An empty or null query should be treated as a request to play any
          * music.
          *
          * @param query The search query.
          * @param extras Optional extras that can include extra information
          *            about the query.
          */
         public abstract void playFromSearch(String query, Bundle extras);

         /**
          * Request that the player start playback for a specific {@link Uri}.
          *
          * @param uri  The URI of the requested media.
          * @param extras Optional extras that can include extra information about the media item
          *               to be played.
          */
         public abstract void playFromUri(Uri uri, Bundle extras);

         /**
          * Plays an item with a specific id in the play queue. If you specify an
          * id that is not in the play queue, the behavior is undefined.
          */
         public abstract void skipToQueueItem(long id);

         /**
          * Request that the player pause its playback and stay at its current
          * position.
          */
         public abstract void pause();

         /**
          * Request that the player stop its playback; it may clear its state in
          * whatever way is appropriate.
          */
         public abstract void stop();

         /**
          * Moves to a new location in the media stream.
          *
          * @param pos Position to move to, in milliseconds.
          */
         public abstract void seekTo(long pos);

         /**
          * Starts fast forwarding. If playback is already fast forwarding this
          * may increase the rate.
          */
         public abstract void fastForward();

         /**
          * Skips to the next item.
          */
         public abstract void skipToNext();

         /**
          * Starts rewinding. If playback is already rewinding this may increase
          * the rate.
          */
         public abstract void rewind();

         /**
          * Skips to the previous item.
          */
         public abstract void skipToPrevious();

         /**
          * Rates the current content. This will cause the rating to be set for
          * the current user. The rating type of the given {@link RatingCompat} must match the type
          * returned by {@link #getRatingType()}.
          *
          * @param rating The rating to set for the current content
          */
         public abstract void setRating(RatingCompat rating);

         /**
          * Rates a media item. This will cause the rating to be set for
          * the specific media item. The rating type of the given {@link RatingCompat} must match
          * the type returned by {@link #getRatingType()}.
          *
          * @param rating The rating to set for the media item.
          * @param extras Optional arguments that can include information about the media item
          *               to be rated.
          *
          * @see MediaSessionCompat#ARGUMENT_MEDIA_ATTRIBUTE
          * @see MediaSessionCompat#ARGUMENT_MEDIA_ATTRIBUTE_VALUE
          */
         public abstract void setRating(RatingCompat rating, Bundle extras);

         /**
          * Sets the playback speed. A value of {@code 1.0f} is the default playback value,
          * and a negative value indicates reverse playback. {@code 0.0f} is not allowed.
          *
          * @param speed The playback speed
          * @throws IllegalArgumentException if the {@code speed} is equal to zero.
          */
         public void setPlaybackSpeed(float speed) {}

         /**
          * Enables/disables captioning for this session.
          *
          * @param enabled {@code true} to enable captioning, {@code false} to disable.
          */
         public abstract void setCaptioningEnabled(boolean enabled);

         /**
          * Sets the repeat mode for this session.
          *
          * @param repeatMode The repeat mode. Must be one of the followings:
          *                   {@link PlaybackStateCompat#REPEAT_MODE_NONE},
          *                   {@link PlaybackStateCompat#REPEAT_MODE_ONE},
          *                   {@link PlaybackStateCompat#REPEAT_MODE_ALL},
          *                   {@link PlaybackStateCompat#REPEAT_MODE_GROUP}
          */
         public abstract void setRepeatMode(@PlaybackStateCompat.RepeatMode int repeatMode);

         /**
          * Sets the shuffle mode for this session.
          *
          * @param shuffleMode The shuffle mode. Must be one of the followings:
          *                    {@link PlaybackStateCompat#SHUFFLE_MODE_NONE},
          *                    {@link PlaybackStateCompat#SHUFFLE_MODE_ALL},
          *                    {@link PlaybackStateCompat#SHUFFLE_MODE_GROUP}
          */
         public abstract void setShuffleMode(@PlaybackStateCompat.ShuffleMode int shuffleMode);

         /**
          * Sends a custom action for the {@link MediaSessionCompat} to perform.
          *
          * @param customAction The action to perform.
          * @param args Optional arguments to supply to the
          *            {@link MediaSessionCompat} for this custom action.
          */
         public abstract void sendCustomAction(PlaybackStateCompat.CustomAction customAction,
                 Bundle args);

         /**
          * Sends the id and args from a custom action for the
          * {@link MediaSessionCompat} to perform.
          *
          * @see #sendCustomAction(PlaybackStateCompat.CustomAction action,
          *      Bundle args)
          * @see MediaSessionCompat#ACTION_FLAG_AS_INAPPROPRIATE
          * @see MediaSessionCompat#ACTION_SKIP_AD
          * @see MediaSessionCompat#ACTION_FOLLOW
          * @see MediaSessionCompat#ACTION_UNFOLLOW
          * @param action The action identifier of the
          *            {@link PlaybackStateCompat.CustomAction} as specified by
          *            the {@link MediaSessionCompat}.
          * @param args Optional arguments to supply to the
          *            {@link MediaSessionCompat} for this custom action.
          */
         public abstract void sendCustomAction(String action, Bundle args);
     }

     /**
      * Holds information about the way volume is handled for this session.
      */
     public static final class PlaybackInfo {
         /**
          * The session uses local playback.
          */
         public static final int PLAYBACK_TYPE_LOCAL = 1;
         /**
          * The session uses remote playback.
          */
         public static final int PLAYBACK_TYPE_REMOTE = 2;

         private final int mPlaybackType;
         private final AudioAttributesCompat mAudioAttrsCompat;
         private final int mVolumeControl;
         private final int mMaxVolume;
         private final int mCurrentVolume;

         PlaybackInfo(int type, int stream, int control, int max, int current) {
             this(type, new AudioAttributesCompat.Builder().setLegacyStreamType(stream).build(),
                     control, max, current);
         }

         PlaybackInfo(int type, @NonNull AudioAttributesCompat attrsCompat,
                 int control, int max, int current) {
             mPlaybackType = type;
             mAudioAttrsCompat = attrsCompat;
             mVolumeControl = control;
             mMaxVolume = max;
             mCurrentVolume = current;
         }

         /**
          * Gets the type of volume handling, either local or remote. One of:
          * <ul>
          * <li>{@link PlaybackInfo#PLAYBACK_TYPE_LOCAL}</li>
          * <li>{@link PlaybackInfo#PLAYBACK_TYPE_REMOTE}</li>
          * </ul>
          *
          * @return The type of volume handling this session is using.
          */
         public int getPlaybackType() {
             return mPlaybackType;
         }

         /**
          * Gets the stream this is currently controlling volume on. When the volume
          * type is {@link PlaybackInfo#PLAYBACK_TYPE_REMOTE} this value does not
          * have meaning and should be ignored.
          *
          * @deprecated Use {@link PlaybackInfo#getAudioAttributes()} instead.
          *
          * @return The stream this session is playing on.
          */
         @Deprecated
         public int getAudioStream() {
             return mAudioAttrsCompat.getLegacyStreamType();
         }

         /**
          * Get the audio attributes for this session. The attributes will affect
          * volume handling for the session. When the volume type is
          * {@link PlaybackInfo#PLAYBACK_TYPE_REMOTE} these may be ignored by the
          * remote volume handler.
          *
          * @return The attributes for this session.
          */
         public @NonNull AudioAttributesCompat getAudioAttributes() {
             return mAudioAttrsCompat;
         }

         /**
          * Gets the type of volume control that can be used. One of:
          * <ul>
          * <li>{@link VolumeProviderCompat#VOLUME_CONTROL_ABSOLUTE}</li>
          * <li>{@link VolumeProviderCompat#VOLUME_CONTROL_RELATIVE}</li>
          * <li>{@link VolumeProviderCompat#VOLUME_CONTROL_FIXED}</li>
          * </ul>
          *
          * @return The type of volume control that may be used with this
          *         session.
          */
         public int getVolumeControl() {
             return mVolumeControl;
         }

         /**
          * Gets the maximum volume that may be set for this session.
          *
          * @return The maximum allowed volume where this session is playing.
          */
         public int getMaxVolume() {
             return mMaxVolume;
         }

         /**
          * Gets the current volume for this session.
          *
          * @return The current volume where this session is playing.
          */
         public int getCurrentVolume() {
             return mCurrentVolume;
         }

     }

     interface MediaControllerImpl {
         void registerCallback(Callback callback, Handler handler);

         void unregisterCallback(Callback callback);
         boolean dispatchMediaButtonEvent(KeyEvent keyEvent);
         TransportControls getTransportControls();
         PlaybackStateCompat getPlaybackState();
         MediaMetadataCompat getMetadata();

         List<QueueItem> getQueue();
         void addQueueItem(MediaDescriptionCompat description);
         void addQueueItem(MediaDescriptionCompat description, int index);
         void removeQueueItem(MediaDescriptionCompat description);
         CharSequence getQueueTitle();
         Bundle getExtras();
         int getRatingType();
         boolean isCaptioningEnabled();
         int getRepeatMode();
         int getShuffleMode();
         long getFlags();
         PlaybackInfo getPlaybackInfo();
         PendingIntent getSessionActivity();

         void setVolumeTo(int value, int flags);
         void adjustVolume(int direction, int flags);
         void sendCommand(String command, Bundle params, ResultReceiver cb);

         boolean isSessionReady();
         String getPackageName();
         Bundle getSessionInfo();
         Object getMediaController();
     }

     static class MediaControllerImplBase implements MediaControllerImpl {
         private IMediaSession mBinder;
         private TransportControls mTransportControls;
         private Bundle mSessionInfo;

         public MediaControllerImplBase(MediaSessionCompat.Token token) {
             mBinder = IMediaSession.Stub.asInterface((IBinder) token.getToken());
         }

         @Override
         public void registerCallback(Callback callback, Handler handler) {
             if (callback == null) {
                 throw new IllegalArgumentException("callback may not be null.");
             }
             try {
                 mBinder.asBinder().linkToDeath(callback, 0);
                 mBinder.registerCallbackListener(callback.mIControllerCallback);
                 callback.postToHandler(Callback.MessageHandler.MSG_SESSION_READY, null, null);
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in registerCallback.", e);
                 callback.postToHandler(Callback.MessageHandler.MSG_DESTROYED, null, null);
             }
         }

         @Override
         public void unregisterCallback(Callback callback) {
             if (callback == null) {
                 throw new IllegalArgumentException("callback may not be null.");
             }
             try {
                 mBinder.unregisterCallbackListener(callback.mIControllerCallback);
                 mBinder.asBinder().unlinkToDeath(callback, 0);
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in unregisterCallback.", e);
             }
         }

         @Override
         public boolean dispatchMediaButtonEvent(KeyEvent event) {
             if (event == null) {
                 throw new IllegalArgumentException("event may not be null.");
             }
             try {
                 mBinder.sendMediaButton(event);
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in dispatchMediaButtonEvent.", e);
             }
             return false;
         }

         @Override
         public TransportControls getTransportControls() {
             if (mTransportControls == null) {
                 mTransportControls = new TransportControlsBase(mBinder);
             }

             return mTransportControls;
         }

         @Override
         public PlaybackStateCompat getPlaybackState() {
             try {
                 return mBinder.getPlaybackState();
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in getPlaybackState.", e);
             }
             return null;
         }

         @Override
         public MediaMetadataCompat getMetadata() {
             try {
                 return mBinder.getMetadata();
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in getMetadata.", e);
             }
             return null;
         }

         @Override
         public List<QueueItem> getQueue() {
             try {
                 return mBinder.getQueue();
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in getQueue.", e);
             }
             return null;
         }

         @Override
         public void addQueueItem(MediaDescriptionCompat description) {
             try {
                 long flags = mBinder.getFlags();
                 if ((flags & MediaSessionCompat.FLAG_HANDLES_QUEUE_COMMANDS) == 0) {
                     throw new UnsupportedOperationException(
                             "This session doesn't support queue management operations");
                 }
                 mBinder.addQueueItem(description);
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in addQueueItem.", e);
             }
         }

         @Override
         public void addQueueItem(MediaDescriptionCompat description, int index) {
             try {
                 long flags = mBinder.getFlags();
                 if ((flags & MediaSessionCompat.FLAG_HANDLES_QUEUE_COMMANDS) == 0) {
                     throw new UnsupportedOperationException(
                             "This session doesn't support queue management operations");
                 }
                 mBinder.addQueueItemAt(description, index);
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in addQueueItemAt.", e);
             }
         }

         @Override
         public void removeQueueItem(MediaDescriptionCompat description) {
             try {
                 long flags = mBinder.getFlags();
                 if ((flags & MediaSessionCompat.FLAG_HANDLES_QUEUE_COMMANDS) == 0) {
                     throw new UnsupportedOperationException(
                             "This session doesn't support queue management operations");
                 }
                 mBinder.removeQueueItem(description);
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in removeQueueItem.", e);
             }
         }

         @Override
         public CharSequence getQueueTitle() {
             try {
                 return mBinder.getQueueTitle();
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in getQueueTitle.", e);
             }
             return null;
         }

         @Override
         public Bundle getExtras() {
             try {
                 return mBinder.getExtras();
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in getExtras.", e);
             }
             return null;
         }

         @Override
         public int getRatingType() {
             try {
                 return mBinder.getRatingType();
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in getRatingType.", e);
             }
             return 0;
         }

         @Override
         public boolean isCaptioningEnabled() {
             try {
                 return mBinder.isCaptioningEnabled();
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in isCaptioningEnabled.", e);
             }
             return false;
         }

         @Override
         public int getRepeatMode() {
             try {
                 return mBinder.getRepeatMode();
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in getRepeatMode.", e);
             }
             return PlaybackStateCompat.REPEAT_MODE_INVALID;
         }

         @Override
         public int getShuffleMode() {
             try {
                 return mBinder.getShuffleMode();
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in getShuffleMode.", e);
             }
             return PlaybackStateCompat.SHUFFLE_MODE_INVALID;
         }

         @Override
         public long getFlags() {
             try {
                 return mBinder.getFlags();
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in getFlags.", e);
             }
             return 0;
         }

         @Override
         public PlaybackInfo getPlaybackInfo() {
             try {
                 ParcelableVolumeInfo info = mBinder.getVolumeAttributes();
                 PlaybackInfo pi = new PlaybackInfo(info.volumeType, info.audioStream,
                         info.controlType, info.maxVolume, info.currentVolume);
                 return pi;
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in getPlaybackInfo.", e);
             }
             return null;
         }

         @Override
         public PendingIntent getSessionActivity() {
             try {
                 return mBinder.getLaunchPendingIntent();
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in getSessionActivity.", e);
             }
             return null;
         }

         @Override
         public void setVolumeTo(int value, int flags) {
             try {
                 mBinder.setVolumeTo(value, flags, null);
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in setVolumeTo.", e);
             }
         }

         @Override
         public void adjustVolume(int direction, int flags) {
             try {
                 mBinder.adjustVolume(direction, flags, null);
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in adjustVolume.", e);
             }
         }

         @Override
         public void sendCommand(String command, Bundle params, ResultReceiver cb) {
             try {
                 mBinder.sendCommand(command, params,
                         cb == null ? null : new MediaSessionCompat.ResultReceiverWrapper(cb));
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in sendCommand.", e);
             }
         }

         @Override
         public boolean isSessionReady() {
             return true;
         }

         @Override
         public String getPackageName() {
             try {
                 return mBinder.getPackageName();
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in getPackageName.", e);
             }
             return null;
         }

         @Override
         public Bundle getSessionInfo() {
             try {
                 mSessionInfo = mBinder.getSessionInfo();
             } catch (RemoteException e) {
                 Log.d(TAG, "Dead object in getSessionInfo.", e);
             }
             return mSessionInfo == null ? Bundle.EMPTY : new Bundle(mSessionInfo);
         }

         @Override
         public Object getMediaController() {
             return null;
         }
     }

     static class TransportControlsBase extends TransportControls {
         private IMediaSession mBinder;

         public TransportControlsBase(IMediaSession binder) {
             mBinder = binder;
         }

         @Override
         public void prepare() {
             try {
                 mBinder.prepare();
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in prepare.", e);
             }
         }

         @Override
         public void prepareFromMediaId(String mediaId, Bundle extras) {
             try {
                 mBinder.prepareFromMediaId(mediaId, extras);
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in prepareFromMediaId.", e);
             }
         }

         @Override
         public void prepareFromSearch(String query, Bundle extras) {
             try {
                 mBinder.prepareFromSearch(query, extras);
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in prepareFromSearch.", e);
             }
         }

         @Override
         public void prepareFromUri(Uri uri, Bundle extras) {
             try {
                 mBinder.prepareFromUri(uri, extras);
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in prepareFromUri.", e);
             }
         }

         @Override
         public void play() {
             try {
                 mBinder.play();
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in play.", e);
             }
         }

         @Override
         public void playFromMediaId(String mediaId, Bundle extras) {
             try {
                 mBinder.playFromMediaId(mediaId, extras);
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in playFromMediaId.", e);
             }
         }

         @Override
         public void playFromSearch(String query, Bundle extras) {
             try {
                 mBinder.playFromSearch(query, extras);
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in playFromSearch.", e);
             }
         }

         @Override
         public void playFromUri(Uri uri, Bundle extras) {
             try {
                 mBinder.playFromUri(uri, extras);
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in playFromUri.", e);
             }
         }

         @Override
         public void skipToQueueItem(long id) {
             try {
                 mBinder.skipToQueueItem(id);
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in skipToQueueItem.", e);
             }
         }

         @Override
         public void pause() {
             try {
                 mBinder.pause();
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in pause.", e);
             }
         }

         @Override
         public void stop() {
             try {
                 mBinder.stop();
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in stop.", e);
             }
         }

         @Override
         public void seekTo(long pos) {
             try {
                 mBinder.seekTo(pos);
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in seekTo.", e);
             }
         }

         @Override
         public void fastForward() {
             try {
                 mBinder.fastForward();
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in fastForward.", e);
             }
         }

         @Override
         public void skipToNext() {
             try {
                 mBinder.next();
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in skipToNext.", e);
             }
         }

         @Override
         public void rewind() {
             try {
                 mBinder.rewind();
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in rewind.", e);
             }
         }

         @Override
         public void skipToPrevious() {
             try {
                 mBinder.previous();
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in skipToPrevious.", e);
             }
         }

         @Override
         public void setRating(RatingCompat rating) {
             try {
                 mBinder.rate(rating);
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in setRating.", e);
             }
         }

         @Override
         public void setRating(RatingCompat rating, Bundle extras) {
             try {
                 mBinder.rateWithExtras(rating, extras);
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in setRating.", e);
             }
         }

         @Override
         public void setPlaybackSpeed(float speed) {
             if (speed == 0.0f) {
                 throw new IllegalArgumentException("speed must not be zero");
             }
             try {
                 mBinder.setPlaybackSpeed(speed);
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in setPlaybackSpeed.", e);
             }
         }

         @Override
         public void setCaptioningEnabled(boolean enabled) {
             try {
                 mBinder.setCaptioningEnabled(enabled);
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in setCaptioningEnabled.", e);
             }
         }

         @Override
         public void setRepeatMode(@PlaybackStateCompat.RepeatMode int repeatMode) {
             try {
                 mBinder.setRepeatMode(repeatMode);
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in setRepeatMode.", e);
             }
         }

         @Override
         public void setShuffleMode(@PlaybackStateCompat.ShuffleMode int shuffleMode) {
             try {
                 mBinder.setShuffleMode(shuffleMode);
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in setShuffleMode.", e);
             }
         }

         @Override
         public void sendCustomAction(CustomAction customAction, Bundle args) {
             sendCustomAction(customAction.getAction(), args);
         }

         @Override
         public void sendCustomAction(String action, Bundle args) {
             validateCustomAction(action, args);
             try {
                 mBinder.sendCustomAction(action, args);
             } catch (RemoteException e) {
                 Log.e(TAG, "Dead object in sendCustomAction.", e);
             }
         }
     }

     @RequiresApi(21)
     static class MediaControllerImplApi21 implements MediaControllerImpl {
         protected final MediaController mControllerFwk;

         final Object mLock = new Object();

         @GuardedBy("mLock")
         private final List<Callback> mPendingCallbacks = new ArrayList<>();

         private HashMap<Callback, ExtraCallback> mCallbackMap = new HashMap<>();

         private Bundle mSessionInfo;

         final MediaSessionCompat.Token mSessionToken;

         public MediaControllerImplApi21(Context context, MediaSessionCompat.Token sessionToken)
                 throws RemoteException {
             mSessionToken = sessionToken;
             mControllerFwk = new MediaController(context,
                     (MediaSession.Token) mSessionToken.getToken());
             if (mControllerFwk == null) throw new RemoteException();
             if (mSessionToken.getExtraBinder() == null) {
                 requestExtraBinder();
             }
         }

         @Override
         public final void registerCallback(Callback callback, Handler handler) {
             mControllerFwk.registerCallback(callback.mCallbackFwk, handler);
             synchronized (mLock) {
                 if (mSessionToken.getExtraBinder() != null) {
                     ExtraCallback extraCallback = new ExtraCallback(callback);
                     mCallbackMap.put(callback, extraCallback);
                     callback.mIControllerCallback = extraCallback;
                     try {
                         mSessionToken.getExtraBinder().registerCallbackListener(extraCallback);
                         callback.postToHandler(
                                 Callback.MessageHandler.MSG_SESSION_READY, null, null);
                     } catch (RemoteException e) {
                         Log.e(TAG, "Dead object in registerCallback.", e);
                     }
                 } else {
                     callback.mIControllerCallback = null;
                     mPendingCallbacks.add(callback);
                 }
             }
         }

         @Override
         public final void unregisterCallback(Callback callback) {
             mControllerFwk.unregisterCallback(callback.mCallbackFwk);
             synchronized (mLock) {
                 if (mSessionToken.getExtraBinder() != null) {
                     try {
                         ExtraCallback extraCallback = mCallbackMap.remove(callback);
                         if (extraCallback != null) {
                             callback.mIControllerCallback = null;
                             mSessionToken.getExtraBinder().unregisterCallbackListener(
                                     extraCallback);
                         }
                     } catch (RemoteException e) {
                         Log.e(TAG, "Dead object in unregisterCallback.", e);
                     }
                 } else {
                     mPendingCallbacks.remove(callback);
                 }
             }
         }

         @Override
         public boolean dispatchMediaButtonEvent(KeyEvent event) {
             return mControllerFwk.dispatchMediaButtonEvent(event);
         }

         @Override
         public TransportControls getTransportControls() {
             return new TransportControlsApi21(mControllerFwk.getTransportControls());
         }

         @Override
         public PlaybackStateCompat getPlaybackState() {
             if (mSessionToken.getExtraBinder() != null) {
                 try {
                     return mSessionToken.getExtraBinder().getPlaybackState();
                 } catch (RemoteException e) {
                     Log.e(TAG, "Dead object in getPlaybackState.", e);
                 }
             }
             PlaybackState stateFwk = mControllerFwk.getPlaybackState();
             return stateFwk != null ? PlaybackStateCompat.fromPlaybackState(stateFwk) : null;
         }

         @Override
         public MediaMetadataCompat getMetadata() {
             MediaMetadata metadataFwk = mControllerFwk.getMetadata();
             return metadataFwk != null ? MediaMetadataCompat.fromMediaMetadata(metadataFwk) : null;
         }

         @Override
         public List<QueueItem> getQueue() {
             List<MediaSession.QueueItem> queueFwks = mControllerFwk.getQueue();
             return queueFwks != null ? QueueItem.fromQueueItemList(queueFwks) : null;
         }

         @Override
         public void addQueueItem(MediaDescriptionCompat description) {
             long flags = getFlags();
             if ((flags & MediaSessionCompat.FLAG_HANDLES_QUEUE_COMMANDS) == 0) {
                 throw new UnsupportedOperationException(
                         "This session doesn't support queue management operations");
             }
             Bundle params = new Bundle();
             params.putParcelable(COMMAND_ARGUMENT_MEDIA_DESCRIPTION, description);
             sendCommand(COMMAND_ADD_QUEUE_ITEM, params, null);
         }

         @Override
         public void addQueueItem(MediaDescriptionCompat description, int index) {
             long flags = getFlags();
             if ((flags & MediaSessionCompat.FLAG_HANDLES_QUEUE_COMMANDS) == 0) {
                 throw new UnsupportedOperationException(
                         "This session doesn't support queue management operations");
             }
             Bundle params = new Bundle();
             params.putParcelable(COMMAND_ARGUMENT_MEDIA_DESCRIPTION, description);
             params.putInt(COMMAND_ARGUMENT_INDEX, index);
             sendCommand(COMMAND_ADD_QUEUE_ITEM_AT, params, null);
         }

         @Override
         public void removeQueueItem(MediaDescriptionCompat description) {
             long flags = getFlags();
             if ((flags & MediaSessionCompat.FLAG_HANDLES_QUEUE_COMMANDS) == 0) {
                 throw new UnsupportedOperationException(
                         "This session doesn't support queue management operations");
             }
             Bundle params = new Bundle();
             params.putParcelable(COMMAND_ARGUMENT_MEDIA_DESCRIPTION, description);
             sendCommand(COMMAND_REMOVE_QUEUE_ITEM, params, null);
         }

         @Override
         public CharSequence getQueueTitle() {
             return mControllerFwk.getQueueTitle();
         }

         @Override
         public Bundle getExtras() {
             return mControllerFwk.getExtras();
         }

         @Override
         public int getRatingType() {
             if (android.os.Build.VERSION.SDK_INT < 22 && mSessionToken.getExtraBinder() != null) {
                 try {
                     return mSessionToken.getExtraBinder().getRatingType();
                 } catch (RemoteException e) {
                     Log.e(TAG, "Dead object in getRatingType.", e);
                 }
             }
             return mControllerFwk.getRatingType();
         }

         @Override
         public boolean isCaptioningEnabled() {
             if (mSessionToken.getExtraBinder() != null) {
                 try {
                     return mSessionToken.getExtraBinder().isCaptioningEnabled();
                 } catch (RemoteException e) {
                     Log.e(TAG, "Dead object in isCaptioningEnabled.", e);
                 }
             }
             return false;
         }

         @Override
         public int getRepeatMode() {
             if (mSessionToken.getExtraBinder() != null) {
                 try {
                     return mSessionToken.getExtraBinder().getRepeatMode();
                 } catch (RemoteException e) {
                     Log.e(TAG, "Dead object in getRepeatMode.", e);
                 }
             }
             return PlaybackStateCompat.REPEAT_MODE_INVALID;
         }

         @Override
         public int getShuffleMode() {
             if (mSessionToken.getExtraBinder() != null) {
                 try {
                     return mSessionToken.getExtraBinder().getShuffleMode();
                 } catch (RemoteException e) {
                     Log.e(TAG, "Dead object in getShuffleMode.", e);
                 }
             }
             return PlaybackStateCompat.SHUFFLE_MODE_INVALID;
         }

         @Override
         public long getFlags() {
             return mControllerFwk.getFlags();
         }

         @Override
         public PlaybackInfo getPlaybackInfo() {
             MediaController.PlaybackInfo volumeInfoFwk = mControllerFwk.getPlaybackInfo();
             return volumeInfoFwk != null ? new PlaybackInfo(
                     volumeInfoFwk.getPlaybackType(),
                     AudioAttributesCompat.wrap(volumeInfoFwk.getAudioAttributes()),
                     volumeInfoFwk.getVolumeControl(),
                     volumeInfoFwk.getMaxVolume(),
                     volumeInfoFwk.getCurrentVolume()) : null;
         }

         @Override
         public PendingIntent getSessionActivity() {
             return mControllerFwk.getSessionActivity();
         }

         @Override
         public void setVolumeTo(int value, int flags) {
             mControllerFwk.setVolumeTo(value, flags);
         }

         @Override
         public void adjustVolume(int direction, int flags) {
             mControllerFwk.adjustVolume(direction, flags);
         }

         @Override
         public void sendCommand(String command, Bundle params, ResultReceiver cb) {
             mControllerFwk.sendCommand(command, params, cb);
         }

         @Override
         public boolean isSessionReady() {
             return mSessionToken.getExtraBinder() != null;
         }

         @Override
         public String getPackageName() {
             return mControllerFwk.getPackageName();
         }

         @Override
         public Bundle getSessionInfo() {
             if (mSessionInfo != null) {
                 return new Bundle(mSessionInfo);
             }

             // Get the info from the connected session.
             if (Build.VERSION.SDK_INT >= 29) {
                 mSessionInfo = mControllerFwk.getSessionInfo();
             } else if (mSessionToken.getExtraBinder() != null) {
                 try {
                     mSessionInfo = mSessionToken.getExtraBinder().getSessionInfo();
                 } catch (RemoteException e) {
                     Log.e(TAG, "Dead object in getSessionInfo.", e);
                     mSessionInfo = Bundle.EMPTY;
                 }
             }
             return mSessionInfo == null ? Bundle.EMPTY : new Bundle(mSessionInfo);
         }

         @Override
         public Object getMediaController() {
             return mControllerFwk;
         }

         private void requestExtraBinder() {
             sendCommand(COMMAND_GET_EXTRA_BINDER, null, new ExtraBinderRequestResultReceiver(this));
         }

         @GuardedBy("mLock")
         void processPendingCallbacksLocked() {
             if (mSessionToken.getExtraBinder() == null) {
                 return;
             }
             for (Callback callback : mPendingCallbacks) {
                 ExtraCallback extraCallback = new ExtraCallback(callback);
                 mCallbackMap.put(callback, extraCallback);
                 callback.mIControllerCallback = extraCallback;
                 try {
                     mSessionToken.getExtraBinder().registerCallbackListener(extraCallback);
                 } catch (RemoteException e) {
                     Log.e(TAG, "Dead object in registerCallback.", e);
                     break;
                 }
                 callback.postToHandler(Callback.MessageHandler.MSG_SESSION_READY, null, null);
             }
             mPendingCallbacks.clear();
         }

         private static class ExtraBinderRequestResultReceiver extends ResultReceiver {
             private WeakReference<MediaControllerImplApi21> mMediaControllerImpl;

             ExtraBinderRequestResultReceiver(MediaControllerImplApi21 mediaControllerImpl) {
                 super(null /* handler */);
                 mMediaControllerImpl = new WeakReference<>(mediaControllerImpl);
             }

             @Override
             protected void onReceiveResult(int resultCode, Bundle resultData) {
                 MediaControllerImplApi21 mediaControllerImpl = mMediaControllerImpl.get();
                 if (mediaControllerImpl == null || resultData == null) {
                     return;
                 }
                 synchronized (mediaControllerImpl.mLock) {
                     mediaControllerImpl.mSessionToken.setExtraBinder(
                             IMediaSession.Stub.asInterface(
                                     BundleCompat.getBinder(
                                             resultData, MediaSessionCompat.KEY_EXTRA_BINDER)));
                     mediaControllerImpl.mSessionToken.setSession2Token(
                             ParcelUtils.getVersionedParcelable(resultData,
                                     MediaSessionCompat.KEY_SESSION2_TOKEN));
                     mediaControllerImpl.processPendingCallbacksLocked();
                 }
             }
         }

         private static class ExtraCallback extends Callback.StubCompat {
             ExtraCallback(Callback callback) {
                 super(callback);
             }

             @Override
             public void onSessionDestroyed() throws RemoteException {
                 // Will not be called.
                 throw new AssertionError();
             }

             @Override
             public void onMetadataChanged(MediaMetadataCompat metadata) throws RemoteException {
                 // Will not be called.
                 throw new AssertionError();
             }

             @Override
             public void onQueueChanged(List<QueueItem> queue) throws RemoteException {
                 // Will not be called.
                 throw new AssertionError();
             }

             @Override
             public void onQueueTitleChanged(CharSequence title) throws RemoteException {
                 // Will not be called.
                 throw new AssertionError();
             }

             @Override
             public void onExtrasChanged(Bundle extras) throws RemoteException {
                 // Will not be called.
                 throw new AssertionError();
             }

             @Override
             public void onVolumeInfoChanged(ParcelableVolumeInfo info) throws RemoteException {
                 // Will not be called.
                 throw new AssertionError();
             }
         }
     }

     @RequiresApi(21)
     static class TransportControlsApi21 extends TransportControls {
         protected final MediaController.TransportControls mControlsFwk;

         TransportControlsApi21(MediaController.TransportControls controlsFwk) {
             mControlsFwk = controlsFwk;
         }

         @Override
         public void prepare() {
             if (Build.VERSION.SDK_INT >= 24) {
                 mControlsFwk.prepare();
                 return;
             }
             sendCustomAction(MediaSessionCompat.ACTION_PREPARE, null);
         }

         @Override
         public void prepareFromMediaId(String mediaId, Bundle extras) {
             if (Build.VERSION.SDK_INT >= 24) {
                 mControlsFwk.prepareFromMediaId(mediaId, extras);
                 return;
             }
             Bundle bundle = new Bundle();
             bundle.putString(MediaSessionCompat.ACTION_ARGUMENT_MEDIA_ID, mediaId);
             bundle.putBundle(MediaSessionCompat.ACTION_ARGUMENT_EXTRAS, extras);
             sendCustomAction(MediaSessionCompat.ACTION_PREPARE_FROM_MEDIA_ID, bundle);
         }

         @Override
         public void prepareFromSearch(String query, Bundle extras) {
             if (Build.VERSION.SDK_INT >= 24) {
                 mControlsFwk.prepareFromSearch(query, extras);
                 return;
             }
             Bundle bundle = new Bundle();
             bundle.putString(MediaSessionCompat.ACTION_ARGUMENT_QUERY, query);
             bundle.putBundle(MediaSessionCompat.ACTION_ARGUMENT_EXTRAS, extras);
             sendCustomAction(MediaSessionCompat.ACTION_PREPARE_FROM_SEARCH, bundle);
         }

         @Override
         public void prepareFromUri(Uri uri, Bundle extras) {
             if (Build.VERSION.SDK_INT >= 24) {
                 mControlsFwk.prepareFromUri(uri, extras);
                 return;
             }
             Bundle bundle = new Bundle();
             bundle.putParcelable(MediaSessionCompat.ACTION_ARGUMENT_URI, uri);
             bundle.putBundle(MediaSessionCompat.ACTION_ARGUMENT_EXTRAS, extras);
             sendCustomAction(MediaSessionCompat.ACTION_PREPARE_FROM_URI, bundle);
         }

         @Override
         public void play() {
             mControlsFwk.play();
         }

         @Override
         public void pause() {
             mControlsFwk.pause();
         }

         @Override
         public void stop() {
             mControlsFwk.stop();
         }

         @Override
         public void seekTo(long pos) {
             mControlsFwk.seekTo(pos);
         }

         @Override
         public void fastForward() {
             mControlsFwk.fastForward();
         }

         @Override
         public void rewind() {
             mControlsFwk.rewind();
         }

         @Override
         public void skipToNext() {
             mControlsFwk.skipToNext();
         }

         @Override
         public void skipToPrevious() {
             mControlsFwk.skipToPrevious();
         }

         @Override
         public void setRating(RatingCompat rating) {
             mControlsFwk.setRating(rating != null ? (Rating) rating.getRating() : null);
         }

         @Override
         public void setRating(RatingCompat rating, Bundle extras) {
             Bundle bundle = new Bundle();
             bundle.putParcelable(MediaSessionCompat.ACTION_ARGUMENT_RATING, rating);
             bundle.putBundle(MediaSessionCompat.ACTION_ARGUMENT_EXTRAS, extras);
             sendCustomAction(MediaSessionCompat.ACTION_SET_RATING, bundle);
         }

         @Override
         public void setPlaybackSpeed(float speed) {
             if (speed == 0.0f) {
                 throw new IllegalArgumentException("speed must not be zero");
             }
             if (Build.VERSION.SDK_INT >= 29) {
                 mControlsFwk.setPlaybackSpeed(speed);
                 return;
             }
             Bundle bundle = new Bundle();
             bundle.putFloat(MediaSessionCompat.ACTION_ARGUMENT_PLAYBACK_SPEED, speed);
             sendCustomAction(MediaSessionCompat.ACTION_SET_PLAYBACK_SPEED, bundle);
         }

         @Override
         public void setCaptioningEnabled(boolean enabled) {
             Bundle bundle = new Bundle();
             bundle.putBoolean(MediaSessionCompat.ACTION_ARGUMENT_CAPTIONING_ENABLED, enabled);
             sendCustomAction(MediaSessionCompat.ACTION_SET_CAPTIONING_ENABLED, bundle);
         }

         @Override
         public void setRepeatMode(@PlaybackStateCompat.RepeatMode int repeatMode) {
             Bundle bundle = new Bundle();
             bundle.putInt(MediaSessionCompat.ACTION_ARGUMENT_REPEAT_MODE, repeatMode);
             sendCustomAction(MediaSessionCompat.ACTION_SET_REPEAT_MODE, bundle);
         }

         @Override
         public void setShuffleMode(@PlaybackStateCompat.ShuffleMode int shuffleMode) {
             Bundle bundle = new Bundle();
             bundle.putInt(MediaSessionCompat.ACTION_ARGUMENT_SHUFFLE_MODE, shuffleMode);
             sendCustomAction(MediaSessionCompat.ACTION_SET_SHUFFLE_MODE, bundle);
         }

         @Override
         public void playFromMediaId(String mediaId, Bundle extras) {
             mControlsFwk.playFromMediaId(mediaId, extras);
         }

         @Override
         public void playFromSearch(String query, Bundle extras) {
             mControlsFwk.playFromSearch(query, extras);
         }

         @Override
         public void playFromUri(Uri uri, Bundle extras) {
             if (Build.VERSION.SDK_INT >= 23) {
                 mControlsFwk.playFromUri(uri, extras);
                 return;
             }
             if (uri == null || Uri.EMPTY.equals(uri)) {
                 throw new IllegalArgumentException(
                         "You must specify a non-empty Uri for playFromUri.");
             }
             Bundle bundle = new Bundle();
             bundle.putParcelable(MediaSessionCompat.ACTION_ARGUMENT_URI, uri);
             bundle.putBundle(MediaSessionCompat.ACTION_ARGUMENT_EXTRAS, extras);
             sendCustomAction(MediaSessionCompat.ACTION_PLAY_FROM_URI, bundle);
         }

         @Override
         public void skipToQueueItem(long id) {
             mControlsFwk.skipToQueueItem(id);
         }

         @Override
         public void sendCustomAction(CustomAction customAction, Bundle args) {
             validateCustomAction(customAction.getAction(), args);
             mControlsFwk.sendCustomAction(customAction.getAction(), args);
         }

         @Override
         public void sendCustomAction(String action, Bundle args) {
             validateCustomAction(action, args);
             mControlsFwk.sendCustomAction(action, args);
         }
     }
 }