components/sync_sessions/session_sync_bridge_unittest.cc - chromium/src - Git at Google

 // Copyright 2018 The Chromium Authors
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #include "components/sync_sessions/session_sync_bridge.h"

 #include <map>
 #include <utility>
 #include <vector>

 #include "base/functional/callback_helpers.h"
 #include "base/memory/raw_ptr.h"
 #include "base/run_loop.h"
 #include "base/test/bind.h"
 #include "base/test/mock_callback.h"
 #include "base/test/task_environment.h"
 #include "components/prefs/testing_pref_service.h"
 #include "components/sync/base/client_tag_hash.h"
 #include "components/sync/engine/commit_and_get_updates_types.h"
 #include "components/sync/engine/data_type_activation_response.h"
 #include "components/sync/model/client_tag_based_model_type_processor.h"
 #include "components/sync/model/data_batch.h"
 #include "components/sync/model/data_type_activation_request.h"
 #include "components/sync/model/metadata_batch.h"
 #include "components/sync/model/metadata_change_list.h"
 #include "components/sync/model/model_type_sync_bridge.h"
 #include "components/sync/protocol/entity_metadata.pb.h"
 #include "components/sync/protocol/model_type_state.pb.h"
 #include "components/sync/protocol/session_specifics.pb.h"
 #include "components/sync/protocol/sync_enums.pb.h"
 #include "components/sync/service/sync_prefs.h"
 #include "components/sync/test/mock_commit_queue.h"
 #include "components/sync/test/mock_model_type_change_processor.h"
 #include "components/sync/test/model_type_store_test_util.h"
 #include "components/sync/test/test_matchers.h"
 #include "components/sync_sessions/mock_sync_sessions_client.h"
 #include "components/sync_sessions/session_sync_prefs.h"
 #include "components/sync_sessions/test_matchers.h"
 #include "components/sync_sessions/test_synced_window_delegates_getter.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"

 namespace sync_sessions {
 namespace {

 using sync_pb::SessionSpecifics;
 using syncer::CommitResponseDataList;
 using syncer::DataBatch;
 using syncer::EntityChangeList;
 using syncer::EntityData;
 using syncer::FailedCommitResponseDataList;
 using syncer::IsEmptyMetadataBatch;
 using syncer::MetadataBatch;
 using syncer::MockModelTypeChangeProcessor;
 using testing::_;
 using testing::AtLeast;
 using testing::ElementsAre;
 using testing::Eq;
 using testing::IsEmpty;
 using testing::IsNull;
 using testing::Not;
 using testing::NotNull;
 using testing::Pair;
 using testing::Pointee;
 using testing::Return;
 using testing::SaveArg;
 using testing::SizeIs;
 using testing::UnorderedElementsAre;
 using testing::WithArg;

 const char kAccountId[] = "TestAccountId";
 const char kLocalCacheGuid[] = "TestLocalCacheGuid";

 MATCHER_P(EntityDataHasSpecifics, session_specifics_matcher, "") {
   return session_specifics_matcher.MatchAndExplain(arg->specifics.session(),
                                                    result_listener);
 }

 sync_pb::ModelTypeState GetModelTypeStateWithInitialSyncDone() {
   sync_pb::ModelTypeState state;
   state.set_initial_sync_state(
       sync_pb::ModelTypeState_InitialSyncState_INITIAL_SYNC_DONE);
   state.set_cache_guid(kLocalCacheGuid);
   state.set_authenticated_account_id(kAccountId);
   state.mutable_progress_marker()->set_data_type_id(
       GetSpecificsFieldNumberFromModelType(syncer::SESSIONS));
   return state;
 }

 syncer::EntityData SpecificsToEntity(const sync_pb::SessionSpecifics& specifics,
                                      base::Time mtime = base::Time::Now()) {
   syncer::EntityData data;
   data.client_tag_hash = syncer::ClientTagHash::FromUnhashed(
       syncer::SESSIONS, SessionStore::GetClientTag(specifics));
   *data.specifics.mutable_session() = specifics;
   data.modification_time = mtime;
   return data;
 }

 syncer::UpdateResponseData SpecificsToUpdateResponse(
     const sync_pb::SessionSpecifics& specifics,
     base::Time mtime = base::Time::Now()) {
   syncer::UpdateResponseData data;
   data.entity = SpecificsToEntity(specifics, mtime);
   return data;
 }

 std::map<std::string, std::unique_ptr<EntityData>> BatchToEntityDataMap(
     std::unique_ptr<DataBatch> batch) {
   std::map<std::string, std::unique_ptr<EntityData>> storage_key_to_data;
   while (batch && batch->HasNext()) {
     storage_key_to_data.insert(batch->Next());
   }
   return storage_key_to_data;
 }

 syncer::UpdateResponseData CreateTombstone(const std::string& client_tag) {
   syncer::EntityData tombstone;

   tombstone.client_tag_hash =
       syncer::ClientTagHash::FromUnhashed(syncer::SESSIONS, client_tag);

   syncer::UpdateResponseData data;
   data.entity = std::move(tombstone);
   data.response_version = 2;
   return data;
 }

 syncer::CommitResponseData CreateSuccessResponse(
     const std::string& client_tag) {
   syncer::CommitResponseData response;
   response.client_tag_hash =
       syncer::ClientTagHash::FromUnhashed(syncer::SESSIONS, client_tag);
   response.sequence_number = 1;
   return response;
 }

 sync_pb::SessionSpecifics CreateHeaderSpecificsWithOneTab(
     const std::string& session_tag,
     int window_id,
     int tab_id) {
   sync_pb::SessionSpecifics specifics;
   specifics.set_session_tag(session_tag);
   specifics.mutable_header()->set_client_name("Some client name");
   specifics.mutable_header()->set_device_type(
       sync_pb::SyncEnums_DeviceType_TYPE_LINUX);
   sync_pb::SessionWindow* window = specifics.mutable_header()->add_window();
   window->set_browser_type(sync_pb::SyncEnums_BrowserType_TYPE_TABBED);
   window->set_window_id(window_id);
   window->add_tab(tab_id);
   return specifics;
 }

 sync_pb::SessionSpecifics CreateTabSpecifics(const std::string& session_tag,
                                              int window_id,
                                              int tab_id,
                                              int tab_node_id,
                                              const std::string& url) {
   sync_pb::SessionSpecifics specifics;
   specifics.set_session_tag(session_tag);
   specifics.set_tab_node_id(tab_node_id);
   specifics.mutable_tab()->add_navigation()->set_virtual_url(url);
   specifics.mutable_tab()->set_window_id(window_id);
   specifics.mutable_tab()->set_tab_id(tab_id);
   return specifics;
 }

 class SessionSyncBridgeTest : public ::testing::Test {
  protected:
   SessionSyncBridgeTest()
       : store_(syncer::ModelTypeStoreTestUtil::CreateInMemoryStoreForTest(
             syncer::SESSIONS)),
         session_sync_prefs_(&pref_service_) {
     SessionSyncPrefs::RegisterProfilePrefs(pref_service_.registry());

     ON_CALL(mock_sync_sessions_client_, GetSessionSyncPrefs())
         .WillByDefault(Return(&session_sync_prefs_));
     ON_CALL(mock_sync_sessions_client_, GetStoreFactory())
         .WillByDefault(
             Return(syncer::ModelTypeStoreTestUtil::FactoryForForwardingStore(
                 store_.get())));
     ON_CALL(mock_sync_sessions_client_, GetSyncedWindowDelegatesGetter())
         .WillByDefault(Return(&window_getter_));
     ON_CALL(mock_sync_sessions_client_, GetLocalSessionEventRouter())
         .WillByDefault(Return(window_getter_.router()));

     // Even if we use NiceMock, let's be strict about errors and let tests
     // explicitly list them.
     EXPECT_CALL(mock_processor_, ReportError).Times(0);
   }

   ~SessionSyncBridgeTest() override = default;

   void InitializeBridge() {
     real_processor_ =
         std::make_unique<syncer::ClientTagBasedModelTypeProcessor>(
             syncer::SESSIONS, /*dump_stack=*/base::DoNothing());
     mock_processor_.DelegateCallsByDefaultTo(real_processor_.get());
     // Instantiate the bridge.
     bridge_ = std::make_unique<SessionSyncBridge>(
         mock_foreign_session_updated_cb_.Get(), &mock_sync_sessions_client_,
         mock_processor_.CreateForwardingProcessor());
   }

   void ShutdownBridge() {
     bridge_.reset();
     // The mock is still delegating to |real_processor_|, so we reset it too.
     ASSERT_TRUE(testing::Mock::VerifyAndClear(&mock_processor_));
     real_processor_.reset();
   }

   void StartSyncing(const std::vector<SessionSpecifics>& remote_data = {}) {
     syncer::DataTypeActivationRequest request;
     request.error_handler = base::DoNothing();
     request.cache_guid = kLocalCacheGuid;
     request.authenticated_account_id = CoreAccountId::FromGaiaId(kAccountId);

     base::RunLoop loop;
     real_processor_->OnSyncStarting(
         request,
         base::BindLambdaForTesting(
             [&loop](std::unique_ptr<syncer::DataTypeActivationResponse>) {
               loop.Quit();
             }));
     loop.Run();

     // ClientTagBasedModelTypeProcessor requires connecting before other
     // interactions with the worker happen.
     real_processor_->ConnectSync(
         std::make_unique<testing::NiceMock<syncer::MockCommitQueue>>());

     sync_pb::ModelTypeState state = GetModelTypeStateWithInitialSyncDone();
     syncer::UpdateResponseDataList initial_updates;
     for (const SessionSpecifics& specifics : remote_data) {
       initial_updates.push_back(SpecificsToUpdateResponse(specifics));
     }
     real_processor_->OnUpdateReceived(state, std::move(initial_updates),
                                       /*gc_directive=*/std::nullopt);
   }

   std::map<std::string, std::unique_ptr<EntityData>> GetAllData() {
     base::RunLoop loop;
     std::unique_ptr<DataBatch> batch;
     bridge_->GetAllDataForDebugging(base::BindLambdaForTesting(
         [&loop, &batch](std::unique_ptr<DataBatch> input_batch) {
           batch = std::move(input_batch);
           loop.Quit();
         }));
     loop.Run();
     EXPECT_NE(nullptr, batch);
     return BatchToEntityDataMap(std::move(batch));
   }

   std::map<std::string, std::unique_ptr<EntityData>> GetData(
       const std::vector<std::string>& storage_keys) {
     base::RunLoop loop;
     std::unique_ptr<DataBatch> batch;
     bridge_->GetData(
         storage_keys,
         base::BindLambdaForTesting(
             [&loop, &batch](std::unique_ptr<DataBatch> input_batch) {
               batch = std::move(input_batch);
               loop.Quit();
             }));
     loop.Run();
     EXPECT_NE(nullptr, batch);
     return BatchToEntityDataMap(std::move(batch));
   }

   std::unique_ptr<EntityData> GetData(const std::string& storage_key) {
     std::map<std::string, std::unique_ptr<EntityData>> entity_data_map =
         GetData(std::vector<std::string>{storage_key});
     EXPECT_LE(entity_data_map.size(), 1U);
     if (entity_data_map.empty()) {
       return nullptr;
     }
     EXPECT_EQ(storage_key, entity_data_map.begin()->first);
     return std::move(entity_data_map.begin()->second);
   }

   void ResetWindows() { window_getter_.ResetWindows(); }

   TestSyncedWindowDelegate* AddWindow(
       int window_id,
       sync_pb::SyncEnums_BrowserType type =
           sync_pb::SyncEnums_BrowserType_TYPE_TABBED) {
     return window_getter_.AddWindow(type,
                                     SessionID::FromSerializedValue(window_id));
   }

   TestSyncedTabDelegate* AddTab(int window_id,
                                 const std::string& url,
                                 int tab_id = SessionID::NewUnique().id()) {
     TestSyncedTabDelegate* tab =
         window_getter_.AddTab(SessionID::FromSerializedValue(window_id),
                               SessionID::FromSerializedValue(tab_id));
     tab->Navigate(url, base::Time::Now());
     return tab;
   }

   void CloseTab(int tab_id) {
     window_getter_.CloseTab(SessionID::FromSerializedValue(tab_id));
   }

   void SessionRestoreComplete() { window_getter_.SessionRestoreComplete(); }

   MockSyncSessionsClient& mock_sync_sessions_client() {
     return mock_sync_sessions_client_;
   }

   base::MockCallback<base::RepeatingClosure>&
   mock_foreign_session_updated_cb() {
     return mock_foreign_session_updated_cb_;
   }

   SessionSyncBridge* bridge() { return bridge_.get(); }

   syncer::MockModelTypeChangeProcessor& mock_processor() {
     return mock_processor_;
   }

   syncer::ClientTagBasedModelTypeProcessor* real_processor() {
     return real_processor_.get();
   }

   syncer::ModelTypeStore* underlying_store() { return store_.get(); }

  private:
   base::test::SingleThreadTaskEnvironment task_environment_;
   const std::unique_ptr<syncer::ModelTypeStore> store_;

   // Dependencies.
   TestingPrefServiceSimple pref_service_;
   SessionSyncPrefs session_sync_prefs_;
   testing::NiceMock<base::MockCallback<base::RepeatingClosure>>
       mock_foreign_session_updated_cb_;
   testing::NiceMock<MockSyncSessionsClient> mock_sync_sessions_client_;
   testing::NiceMock<MockModelTypeChangeProcessor> mock_processor_;
   TestSyncedWindowDelegatesGetter window_getter_;

   std::unique_ptr<SessionSyncBridge> bridge_;
   std::unique_ptr<syncer::ClientTagBasedModelTypeProcessor> real_processor_;
 };

 TEST_F(SessionSyncBridgeTest, ShouldCallModelReadyToSyncWhenSyncEnabled) {
   EXPECT_CALL(mock_processor(), ModelReadyToSync).Times(0);
   InitializeBridge();
   EXPECT_CALL(mock_processor(), ModelReadyToSync(IsEmptyMetadataBatch()));
   StartSyncing();
 }

 // Test that handling of local events (i.e. propagating the local state to
 // sync) does not start while a session restore is in progress.
 TEST_F(SessionSyncBridgeTest, ShouldDeferLocalEventDueToSessionRestore) {
   const int kWindowId = 1000001;
   const int kTabId1 = 1000002;
   const int kTabId2 = 1000003;

   // No notifications expected until OnSessionRestoreComplete().
   EXPECT_CALL(mock_processor(), Put).Times(0);

   AddWindow(kWindowId)->SetIsSessionRestoreInProgress(true);
   // Initial tab should be ignored (not exposed to processor) while session
   // restore is in progress.
   AddTab(kWindowId, "http://foo.com/", kTabId1);

   InitializeBridge();
   StartSyncing();
   EXPECT_THAT(GetAllData(),
               ElementsAre(Pair(
                   _, EntityDataHasSpecifics(MatchesHeader(kLocalCacheGuid,
                                                           /*window_ids=*/{},
                                                           /*tab_ids=*/{})))));

   // Create the actual tab, which should be ignored because session restore
   // is in progress.
   AddTab(kWindowId, "http://bar.com/", kTabId2);
   EXPECT_THAT(GetAllData(), SizeIs(1));

   // OnSessionRestoreComplete() should issue three Put() calls, one updating the
   // header and one for each of the two added tabs.
   EXPECT_CALL(mock_processor(), Put).Times(3);
   SessionRestoreComplete();
   EXPECT_THAT(GetAllData(), SizeIs(3));
 }

 TEST_F(SessionSyncBridgeTest, ShouldCreateHeaderByDefault) {
   InitializeBridge();

   EXPECT_CALL(mock_processor(), ModelReadyToSync(IsEmptyMetadataBatch()));
   StartSyncing();

   EXPECT_THAT(GetAllData(), SizeIs(1));
 }

 // Tests that local windows and tabs that exist at the time the bridge is
 // started (e.g. after a Chrome restart) are properly exposed via the bridge's
 // GetData() and GetAllData() methods, as well as notified via Put().
 TEST_F(SessionSyncBridgeTest, ShouldExposeInitialLocalTabsToProcessor) {
   const int kWindowId = 1000001;
   const int kTabId1 = 1000002;
   const int kTabId2 = 1000003;

   AddWindow(kWindowId);
   AddTab(kWindowId, "http://foo.com/", kTabId1);
   AddTab(kWindowId, "http://bar.com/", kTabId2);

   InitializeBridge();

   const std::string header_storage_key =
       SessionStore::GetHeaderStorageKey(kLocalCacheGuid);
   const std::string tab_storage_key1 =
       SessionStore::GetTabStorageKey(kLocalCacheGuid, 0);
   const std::string tab_storage_key2 =
       SessionStore::GetTabStorageKey(kLocalCacheGuid, 1);

   EXPECT_CALL(mock_processor(),
               Put(header_storage_key,
                   EntityDataHasSpecifics(MatchesHeader(
                       kLocalCacheGuid, {kWindowId}, {kTabId1, kTabId2})),
                   _));
   EXPECT_CALL(mock_processor(),
               Put(tab_storage_key1,
                   EntityDataHasSpecifics(
                       MatchesTab(kLocalCacheGuid, kWindowId, kTabId1,
                                  /*tab_node_id=*/_, {"http://foo.com/"})),
                   _));
   EXPECT_CALL(mock_processor(),
               Put(tab_storage_key2,
                   EntityDataHasSpecifics(
                       MatchesTab(kLocalCacheGuid, kWindowId, kTabId2,
                                  /*tab_node_id=*/_, {"http://bar.com/"})),
                   _));

   StartSyncing();

   EXPECT_THAT(GetData(header_storage_key),
               EntityDataHasSpecifics(MatchesHeader(kLocalCacheGuid, {kWindowId},
                                                    {kTabId1, kTabId2})));
   EXPECT_THAT(
       GetAllData(),
       UnorderedElementsAre(
           Pair(header_storage_key,
                EntityDataHasSpecifics(MatchesHeader(
                    kLocalCacheGuid, {kWindowId}, {kTabId1, kTabId2}))),
           Pair(tab_storage_key1, EntityDataHasSpecifics(MatchesTab(
                                      kLocalCacheGuid, kWindowId, kTabId1,
                                      /*tab_node_id=*/_, {"http://foo.com/"}))),
           Pair(tab_storage_key2,
                EntityDataHasSpecifics(
                    MatchesTab(kLocalCacheGuid, kWindowId, kTabId2,
                               /*tab_node_id=*/_, {"http://bar.com/"})))));
 }

 // Tests that the creation of a new tab while sync is enabled is propagated to:
 // 1) The processor, via Put().
 // 2) The in-memory representation exposed via GetData().
 // 3) The persisted store, exposed via GetAllData().
 TEST_F(SessionSyncBridgeTest, ShouldReportLocalTabCreation) {
   const int kWindowId = 1000001;
   const int kTabId1 = 1000002;
   const int kTabId2 = 1000003;

   AddWindow(kWindowId);
   AddTab(kWindowId, "http://foo.com/", kTabId1);

   InitializeBridge();
   StartSyncing();

   ASSERT_THAT(GetAllData(), SizeIs(2));
   EXPECT_CALL(mock_foreign_session_updated_cb(), Run()).Times(0);

   // Expectations for the processor.
   std::string header_storage_key;
   std::string tab_storage_key;
   // Tab creation triggers an update event due to the tab parented notification,
   // so the event handler issues two commits as well (one for tab creation, one
   // for tab update). During the first update, however, the tab is not syncable
   // and is hence skipped.
   testing::Expectation put_transient_header = EXPECT_CALL(
       mock_processor(), Put(_,
                             EntityDataHasSpecifics(MatchesHeader(
                                 kLocalCacheGuid, {kWindowId}, {kTabId1})),
                             _));
   EXPECT_CALL(mock_processor(),
               Put(_,
                   EntityDataHasSpecifics(MatchesHeader(
                       kLocalCacheGuid, {kWindowId}, {kTabId1, kTabId2})),
                   _))
       .After(put_transient_header)
       .WillOnce(WithArg<0>(SaveArg<0>(&header_storage_key)));
   EXPECT_CALL(mock_processor(),
               Put(_,
                   EntityDataHasSpecifics(
                       MatchesTab(kLocalCacheGuid, kWindowId, kTabId2,
                                  /*tab_node_id=*/_, {"http://bar.com/"})),
                   _))
       .WillOnce(WithArg<0>(SaveArg<0>(&tab_storage_key)));

   // Create the actual tab, now that we're syncing.
   AddTab(kWindowId, "http://bar.com/", kTabId2);

   ASSERT_THAT(header_storage_key,
               Eq(SessionStore::GetHeaderStorageKey(kLocalCacheGuid)));
   ASSERT_THAT(tab_storage_key, Not(IsEmpty()));

   // Verify the bridge's state exposed via the getters.
   EXPECT_THAT(
       GetAllData(),
       UnorderedElementsAre(
           Pair(header_storage_key,
                EntityDataHasSpecifics(MatchesHeader(
                    kLocalCacheGuid, {kWindowId}, {kTabId1, kTabId2}))),
           Pair(_, EntityDataHasSpecifics(
                       MatchesTab(kLocalCacheGuid, kWindowId, kTabId1,
                                  /*tab_node_id=*/_, {"http://foo.com/"}))),
           Pair(tab_storage_key, EntityDataHasSpecifics(MatchesTab(
                                     kLocalCacheGuid, kWindowId, kTabId2,
                                     /*tab_node_id=*/_, {"http://bar.com/"})))));
   EXPECT_THAT(GetData(header_storage_key),
               EntityDataHasSpecifics(MatchesHeader(kLocalCacheGuid, {kWindowId},
                                                    {kTabId1, kTabId2})));
   EXPECT_THAT(GetData(tab_storage_key),
               EntityDataHasSpecifics(
                   MatchesTab(kLocalCacheGuid, kWindowId, kTabId2,
                              /*tab_node_id=*/_, {"http://bar.com/"})));
 }

 TEST_F(SessionSyncBridgeTest, ShouldNotUpdatePlaceholderTabsDuringRestore) {
   const int kWindowId1 = 1000001;
   const int kWindowId2 = 1000002;
   const int kTabId1 = 1000003;
   const int kTabId2 = 1000004;
   // Zero is the first assigned tab node ID.
   const int kTabNodeId1 = 0;
   const int kTabNodeId2 = 1;

   AddWindow(kWindowId1);
   AddTab(kWindowId1, "http://foo.com/", kTabId1);
   AddTab(kWindowId1, "http://bar.com/", kTabId2);

   const std::string header_storage_key =
       SessionStore::GetHeaderStorageKey(kLocalCacheGuid);
   const std::string tab_storage_key1 =
       SessionStore::GetTabStorageKey(kLocalCacheGuid, kTabNodeId1);
   const std::string tab_storage_key2 =
       SessionStore::GetTabStorageKey(kLocalCacheGuid, kTabNodeId2);

   InitializeBridge();
   StartSyncing();

   ASSERT_THAT(GetData(header_storage_key),
               EntityDataHasSpecifics(MatchesHeader(
                   kLocalCacheGuid, {kWindowId1}, {kTabId1, kTabId2})));
   ASSERT_THAT(
       GetData(tab_storage_key1),
       EntityDataHasSpecifics(MatchesTab(kLocalCacheGuid, kWindowId1, kTabId1,
                                         kTabNodeId1, {"http://foo.com/"})));
   ASSERT_THAT(
       GetData(tab_storage_key2),
       EntityDataHasSpecifics(MatchesTab(kLocalCacheGuid, kWindowId1, kTabId2,
                                         kTabNodeId2, {"http://bar.com/"})));

   ShutdownBridge();

   // Override tabs with placeholder tab delegates. Note that, on Android, tab
   // IDs are persisted by session restore across browser restarts.
   PlaceholderTabDelegate placeholder_tab1(
       SessionID::FromSerializedValue(kTabId1));
   PlaceholderTabDelegate placeholder_tab2(
       SessionID::FromSerializedValue(kTabId2));
   ResetWindows();
   TestSyncedWindowDelegate* window = AddWindow(kWindowId2);
   window->OverrideTabAt(0, &placeholder_tab1);
   window->OverrideTabAt(1, &placeholder_tab2);

   // When the bridge gets restarted, we only expect the header to be updated,
   // and placeholder tabs stay unchanged with a stale window ID.
   EXPECT_CALL(mock_processor(),
               Put(header_storage_key,
                   EntityDataHasSpecifics(MatchesHeader(
                       kLocalCacheGuid, {kWindowId2}, {kTabId1, kTabId2})),
                   _));

   // Start the bridge again.
   InitializeBridge();
   StartSyncing();

   // Although we haven't notified the processor about the window-ID change, if
   // it hypothetically asked for these entities, the returned entities are
   // up-to-date.
   EXPECT_THAT(GetData(header_storage_key),
               EntityDataHasSpecifics(MatchesHeader(
                   kLocalCacheGuid, {kWindowId2}, {kTabId1, kTabId2})));
   EXPECT_THAT(
       GetData(tab_storage_key1),
       EntityDataHasSpecifics(MatchesTab(kLocalCacheGuid, kWindowId2, kTabId1,
                                         kTabNodeId1, {"http://foo.com/"})));
   EXPECT_THAT(
       GetData(tab_storage_key2),
       EntityDataHasSpecifics(MatchesTab(kLocalCacheGuid, kWindowId2, kTabId2,
                                         kTabNodeId2, {"http://bar.com/"})));

   EXPECT_THAT(
       GetAllData(),
       UnorderedElementsAre(
           Pair(header_storage_key,
                EntityDataHasSpecifics(MatchesHeader(
                    kLocalCacheGuid, {kWindowId2}, {kTabId1, kTabId2}))),
           Pair(tab_storage_key1, EntityDataHasSpecifics(MatchesTab(
                                      kLocalCacheGuid, kWindowId2, kTabId1,
                                      kTabNodeId1, {"http://foo.com/"}))),
           Pair(tab_storage_key2, EntityDataHasSpecifics(MatchesTab(
                                      kLocalCacheGuid, kWindowId2, kTabId2,
                                      kTabNodeId2, {"http://bar.com/"})))));
 }

 TEST_F(SessionSyncBridgeTest,
        ShouldIgnoreUnsyncablePlaceholderTabDuringRestore) {
   const int kWindowId1 = 1000001;
   const int kWindowId2 = 1000002;
   const int kTabId1 = 1000002;
   const int kTabId2 = 1000003;
   // Zero is the first assigned tab node ID.
   const int kTabNodeId1 = 0;

   AddWindow(kWindowId1);
   AddTab(kWindowId1, "http://foo.com/", kTabId1);
   // Tab 2 is unsyncable because of the URL scheme.
   AddTab(kWindowId1, "about:blank", kTabId2);

   const std::string header_storage_key =
       SessionStore::GetHeaderStorageKey(kLocalCacheGuid);
   const std::string tab_storage_key1 =
       SessionStore::GetTabStorageKey(kLocalCacheGuid, kTabNodeId1);

   InitializeBridge();
   StartSyncing();

   ASSERT_THAT(
       GetAllData(),
       UnorderedElementsAre(
           Pair(header_storage_key,
                EntityDataHasSpecifics(
                    MatchesHeader(kLocalCacheGuid, {kWindowId1}, {kTabId1}))),
           Pair(tab_storage_key1, EntityDataHasSpecifics(MatchesTab(
                                      kLocalCacheGuid, kWindowId1, kTabId1,
                                      kTabNodeId1, {"http://foo.com/"})))));

   ShutdownBridge();

   // Override tabs with placeholder tab delegates. Note that, on Android, tab
   // IDs are persisted by session restore across browser restarts.
   PlaceholderTabDelegate placeholder_tab1(
       SessionID::FromSerializedValue(kTabId1));
   auto snapshot1 = std::make_unique<TestSyncedTabDelegate>(
       SessionID::FromSerializedValue(kWindowId1),
       SessionID::FromSerializedValue(kTabId1), base::DoNothing());
   placeholder_tab1.SetPlaceholderTabSyncedTabDelegate(std::move(snapshot1));

   PlaceholderTabDelegate placeholder_tab2(
       SessionID::FromSerializedValue(kTabId2));
   auto snapshot2 = std::make_unique<TestSyncedTabDelegate>(
       SessionID::FromSerializedValue(kWindowId2),
       SessionID::FromSerializedValue(kTabId2), base::DoNothing());
   placeholder_tab2.SetPlaceholderTabSyncedTabDelegate(std::move(snapshot2));

   ResetWindows();
   TestSyncedWindowDelegate* window = AddWindow(kWindowId2);
   window->OverrideTabAt(0, &placeholder_tab1);
   window->OverrideTabAt(1, &placeholder_tab2);

   // Start the bridge again.
   InitializeBridge();
   StartSyncing();

   EXPECT_THAT(
       GetAllData(),
       UnorderedElementsAre(
           Pair(header_storage_key,
                EntityDataHasSpecifics(
                    MatchesHeader(kLocalCacheGuid, {kWindowId2}, {kTabId1}))),
           Pair(tab_storage_key1, EntityDataHasSpecifics(MatchesTab(
                                      kLocalCacheGuid, kWindowId2, kTabId1,
                                      kTabNodeId1, {"http://foo.com/"})))));
 }

 // Ensure that tabbed windows from a previous session are preserved if no
 // windows are present on startup.
 TEST_F(SessionSyncBridgeTest, ShouldRestoreTabbedDataIfNoWindowsDuringStartup) {
   const int kWindowId1 = 1000001;
   const int kWindowId2 = 1000002;
   const int kTabNodeId = 0;

   AddWindow(kWindowId1);
   TestSyncedTabDelegate* tab = AddTab(kWindowId1, "http://foo.com/");

   const std::string header_storage_key =
       SessionStore::GetHeaderStorageKey(kLocalCacheGuid);
   const std::string tab_storage_key =
       SessionStore::GetTabStorageKey(kLocalCacheGuid, kTabNodeId);

   InitializeBridge();
   StartSyncing();

   ASSERT_THAT(
       GetAllData(),
       UnorderedElementsAre(
           Pair(header_storage_key,
                EntityDataHasSpecifics(MatchesHeader(kLocalCacheGuid, _, _))),
           Pair(tab_storage_key,
                EntityDataHasSpecifics(MatchesTab(
                    kLocalCacheGuid, _, _, kTabNodeId, {"http://foo.com/"})))));

   ShutdownBridge();

   // Start the bridge with no local windows/tabs.
   ResetWindows();
   InitializeBridge();
   StartSyncing();

   EXPECT_THAT(
       GetAllData(),
       UnorderedElementsAre(
           Pair(header_storage_key,
                EntityDataHasSpecifics(MatchesHeader(kLocalCacheGuid, _, _))),
           Pair(tab_storage_key,
                EntityDataHasSpecifics(MatchesTab(
                    kLocalCacheGuid, _, _, kTabNodeId, {"http://foo.com/"})))));

   // Now actually resurrect the native data, which will end up having different
   // native ids, but the tab has the same sync id as before.
   EXPECT_CALL(
       mock_processor(),
       Put(header_storage_key,
           EntityDataHasSpecifics(MatchesHeader(kLocalCacheGuid, _, _)), _));
   EXPECT_CALL(mock_processor(),
               Put(tab_storage_key,
                   EntityDataHasSpecifics(MatchesTab(
                       kLocalCacheGuid, /*window_id=*/_, /*tab_id=*/_,
                       kTabNodeId, {"http://foo.com/", "http://bar.com/"})),
                   _));
   AddWindow(kWindowId2)->OverrideTabAt(0, tab);
   tab->Navigate("http://bar.com/");
 }

 // Ensure that tabbed windows from a previous session are preserved if only
 // a custom tab is present at startup.
 TEST_F(SessionSyncBridgeTest, ShouldPreserveTabbedDataIfCustomTabOnlyFound) {
   const int kWindowId1 = 1000001;
   const int kWindowId2 = 1000002;

   AddWindow(kWindowId1);
   AddTab(kWindowId1, "http://foo.com/");

   InitializeBridge();
   StartSyncing();

   ASSERT_THAT(
       GetAllData(),
       UnorderedElementsAre(
           Pair(_, EntityDataHasSpecifics(MatchesHeader(kLocalCacheGuid, _, _))),
           Pair(_, EntityDataHasSpecifics(MatchesTab(kLocalCacheGuid, _, _,
                                                     /*tab_node_id=*/0,
                                                     {"http://foo.com/"})))));

   ShutdownBridge();

   // Start the bridge with only a custom tab open.
   ResetWindows();
   AddWindow(kWindowId2, sync_pb::SyncEnums_BrowserType_TYPE_CUSTOM_TAB);
   AddTab(kWindowId2, "http://bar.com/");
   InitializeBridge();
   StartSyncing();

   // The previous session should be preserved, together with the new custom tab.
   EXPECT_THAT(
       GetAllData(),
       UnorderedElementsAre(
           Pair(_, EntityDataHasSpecifics(MatchesHeader(kLocalCacheGuid, _, _))),
           Pair(_, EntityDataHasSpecifics(MatchesTab(kLocalCacheGuid, _, _,
                                                     /*tab_node_id=*/0,
                                                     {"http://foo.com/"}))),
           Pair(_, EntityDataHasSpecifics(MatchesTab(kLocalCacheGuid, _, _,
                                                     /*tab_node_id=*/1,
                                                     {"http://bar.com/"})))));
 }

 // Ensure that tabbed windows from a previous session are preserved and combined
 // with a custom tab that was newly found during startup.
 TEST_F(SessionSyncBridgeTest, ShouldPreserveTabbedDataIfNewCustomTabAlsoFound) {
   const int kWindowId1 = 1000001;
   const int kWindowId2 = 1000002;
   const int kTabId1 = 1000003;
   const int kTabId2 = 1000004;

   AddWindow(kWindowId1);
   AddTab(kWindowId1, "http://foo.com/", kTabId1);

   InitializeBridge();
   StartSyncing();

   ASSERT_THAT(GetAllData(),
               UnorderedElementsAre(
                   Pair(_, EntityDataHasSpecifics(MatchesHeader(
                               kLocalCacheGuid, {kWindowId1}, {kTabId1}))),
                   Pair(_, EntityDataHasSpecifics(MatchesTab(
                               kLocalCacheGuid, kWindowId1, kTabId1,
                               /*tab_node_id=*/0, {"http://foo.com/"})))));

   ShutdownBridge();

   // Start the bridge with an additional local custom tab.
   AddWindow(kWindowId2, sync_pb::SyncEnums_BrowserType_TYPE_CUSTOM_TAB);
   AddTab(kWindowId2, "http://bar.com/", kTabId2);
   InitializeBridge();
   StartSyncing();

   EXPECT_THAT(GetAllData(),
               UnorderedElementsAre(
                   Pair(_, EntityDataHasSpecifics(MatchesHeader(
                               kLocalCacheGuid, {kWindowId1, kWindowId2},
                               {kTabId1, kTabId2}))),
                   Pair(_, EntityDataHasSpecifics(MatchesTab(
                               kLocalCacheGuid, kWindowId1, kTabId1,
                               /*tab_node_id=*/0, {"http://foo.com/"}))),
                   Pair(_, EntityDataHasSpecifics(MatchesTab(
                               kLocalCacheGuid, kWindowId2, kTabId2,
                               /*tab_node_id=*/1, {"http://bar.com/"})))));
 }

 // Ensure that, in a scenario without prior sync data, encountering a custom
 // tab only (no tabbed window) starts syncing that tab.
 TEST_F(SessionSyncBridgeTest, ShouldAssociateIfCustomTabOnlyOnStartup) {
   const int kWindowId = 1000001;
   const int kTabId = 1000002;

   AddWindow(kWindowId, sync_pb::SyncEnums_BrowserType_TYPE_CUSTOM_TAB);
   AddTab(kWindowId, "http://foo.com/", kTabId);

   InitializeBridge();
   StartSyncing();

   EXPECT_THAT(GetAllData(),
               UnorderedElementsAre(
                   Pair(_, EntityDataHasSpecifics(MatchesHeader(
                               kLocalCacheGuid, {kWindowId}, {kTabId}))),
                   Pair(_, EntityDataHasSpecifics(MatchesTab(
                               kLocalCacheGuid, kWindowId, kTabId,
                               /*tab_node_id=*/0, {"http://foo.com/"})))));
 }

 // Ensure that all tabs are exposed in a scenario where only a custom tab
 // (without tabbed windows) was present during startup, and later tabbed windows
 // appear (browser started).
 TEST_F(SessionSyncBridgeTest, ShouldExposeTabbedWindowAfterCustomTabOnly) {
   const int kWindowId1 = 1000001;
   const int kWindowId2 = 1000002;
   const int kTabId1 = 1000003;
   const int kTabId2 = 1000004;

   AddWindow(kWindowId1, sync_pb::SyncEnums_BrowserType_TYPE_CUSTOM_TAB);
   AddTab(kWindowId1, "http://foo.com/", kTabId1);

   InitializeBridge();
   StartSyncing();

   ASSERT_THAT(GetAllData(),
               UnorderedElementsAre(
                   Pair(_, EntityDataHasSpecifics(MatchesHeader(
                               kLocalCacheGuid, {kWindowId1}, {kTabId1}))),
                   Pair(_, EntityDataHasSpecifics(MatchesTab(
                               kLocalCacheGuid, kWindowId1, kTabId1,
                               /*tab_node_id=*/0, {"http://foo.com/"})))));

   // Load the actual tabbed window, now that we're syncing.
   AddWindow(kWindowId2);
   AddTab(kWindowId2, "http://bar.com/", kTabId2);

   // The local change should be created and tracked correctly.
   EXPECT_THAT(GetAllData(),
               UnorderedElementsAre(
                   Pair(_, EntityDataHasSpecifics(MatchesHeader(
                               kLocalCacheGuid, {kWindowId1, kWindowId2},
                               {kTabId1, kTabId2}))),
                   Pair(_, EntityDataHasSpecifics(MatchesTab(
                               kLocalCacheGuid, kWindowId1, kTabId1,
                               /*tab_node_id=*/0, {"http://foo.com/"}))),
                   Pair(_, EntityDataHasSpecifics(MatchesTab(
                               kLocalCacheGuid, kWindowId2, kTabId2,
                               /*tab_node_id=*/1, {"http://bar.com/"})))));
 }

 TEST_F(SessionSyncBridgeTest, ShouldRecycleTabNodeAfterCommitCompleted) {
   const int kWindowId = 1000001;
   const int kTabId1 = 1000003;
   const int kTabId2 = 1000004;
   const int kTabId3 = 1000005;
   const int kTabId4 = 1000006;
   // Zero is the first assigned tab node ID.
   const int kTabNodeId1 = 0;
   const int kTabNodeId2 = 1;
   const int kTabNodeId3 = 2;

   AddWindow(kWindowId);
   TestSyncedTabDelegate* tab1 = AddTab(kWindowId, "http://foo.com/", kTabId1);

   const std::string header_storage_key =
       SessionStore::GetHeaderStorageKey(kLocalCacheGuid);
   const std::string tab_storage_key1 =
       SessionStore::GetTabStorageKey(kLocalCacheGuid, kTabNodeId1);
   const std::string tab_storage_key2 =
       SessionStore::GetTabStorageKey(kLocalCacheGuid, kTabNodeId2);
   const std::string tab_storage_key3 =
       SessionStore::GetTabStorageKey(kLocalCacheGuid, kTabNodeId3);
   const std::string tab_client_tag1 =
       SessionStore::GetTabClientTagForTest(kLocalCacheGuid, kTabNodeId1);
   const std::string tab_client_tag2 =
       SessionStore::GetTabClientTagForTest(kLocalCacheGuid, kTabNodeId2);
   const std::string tab_client_tag3 =
       SessionStore::GetTabClientTagForTest(kLocalCacheGuid, kTabNodeId3);

   InitializeBridge();
   StartSyncing();

   // Mimic a commit completing for the initial sync.
   ASSERT_TRUE(real_processor()->HasLocalChangesForTest());
   real_processor()->OnCommitCompleted(
       GetModelTypeStateWithInitialSyncDone(),
       {CreateSuccessResponse(kLocalCacheGuid),
        CreateSuccessResponse(tab_client_tag1)},
       /*error_response_list=*/FailedCommitResponseDataList());
   ASSERT_FALSE(real_processor()->HasLocalChangesForTest());

   // Open a second tab.
   AddTab(kWindowId, "http://bar.com/", kTabId2);
   ASSERT_TRUE(real_processor()->HasLocalChangesForTest());

   // Close |kTabId2| and force reassociation by navigating in the remaining open
   // tab, leading to a freed tab entity. However, while there are pending
   // changes to commit, the entity shouldn't be deleted (to prevent history
   // loss).
   EXPECT_CALL(mock_processor(), Delete).Times(0);
   CloseTab(kTabId2);
   tab1->Navigate("http://foo2.com/");
   EXPECT_TRUE(real_processor()->HasLocalChangesForTest());

   EXPECT_THAT(
       GetAllData(),
       UnorderedElementsAre(
           Pair(header_storage_key,
                EntityDataHasSpecifics(
                    MatchesHeader(kLocalCacheGuid, {kWindowId}, {kTabId1}))),
           Pair(tab_storage_key1,
                EntityDataHasSpecifics(
                    MatchesTab(kLocalCacheGuid, kWindowId, kTabId1, kTabNodeId1,
                               {"http://foo.com/", "http://foo2.com/"}))),
           Pair(tab_storage_key2, EntityDataHasSpecifics(MatchesTab(
                                      kLocalCacheGuid, kWindowId, kTabId2,
                                      kTabNodeId2, {"http://bar.com/"})))));

   // If a new tab is opened, the entity with unsynced changes should not be
   // recycled.
   AddTab(kWindowId, "http://baz.com/", kTabId3);
   EXPECT_THAT(GetAllData(), UnorderedElementsAre(Pair(header_storage_key, _),
                                                  Pair(tab_storage_key1, _),
                                                  Pair(tab_storage_key2, _),
                                                  Pair(tab_storage_key3, _)));

   // Completing the commit for the previously closed tab should issue a
   // deletion. For that to trigger, we need to trigger the next association,
   // which we do by navigating in one of the open tabs.
   EXPECT_CALL(mock_processor(), Delete(tab_storage_key2, _));
   real_processor()->OnCommitCompleted(
       GetModelTypeStateWithInitialSyncDone(),
       {CreateSuccessResponse(tab_client_tag2)},
       /*error_response_list=*/FailedCommitResponseDataList());
   tab1->Navigate("http://foo3.com/");
   EXPECT_THAT(GetAllData(), UnorderedElementsAre(Pair(header_storage_key, _),
                                                  Pair(tab_storage_key1, _),
                                                  Pair(tab_storage_key3, _)));

   // If yet anothertab is opened, the entity for the closed tab should be
   // recycled.
   AddTab(kWindowId, "http://qux.com/", kTabId4);
   EXPECT_THAT(
       GetAllData(),
       UnorderedElementsAre(
           Pair(header_storage_key, _), Pair(tab_storage_key1, _),
           Pair(tab_storage_key2, EntityDataHasSpecifics(MatchesTab(
                                      kLocalCacheGuid, kWindowId, kTabId4,
                                      kTabNodeId2, {"http://qux.com/"}))),
           Pair(tab_storage_key3, _)));
 }

 TEST_F(SessionSyncBridgeTest, ShouldRestoreLocalSessionWithFreedTab) {
   const int kWindowId1 = 1000001;
   const int kWindowId2 = 1000002;
   const int kTabId1 = 1000003;
   const int kTabId2 = 1000004;
   const int kTabId3 = 1000005;
   // Zero is the first assigned tab node ID.
   const int kTabNodeId1 = 0;
   const int kTabNodeId2 = 1;
   const int kTabNodeId3 = 2;

   AddWindow(kWindowId1);
   TestSyncedTabDelegate* tab1 = AddTab(kWindowId1, "http://foo.com/", kTabId1);
   AddTab(kWindowId1, "http://bar.com/", kTabId2);

   const std::string header_storage_key =
       SessionStore::GetHeaderStorageKey(kLocalCacheGuid);
   const std::string tab_storage_key1 =
       SessionStore::GetTabStorageKey(kLocalCacheGuid, kTabNodeId1);
   const std::string tab_storage_key2 =
       SessionStore::GetTabStorageKey(kLocalCacheGuid, kTabNodeId2);
   const std::string tab_storage_key3 =
       SessionStore::GetTabStorageKey(kLocalCacheGuid, kTabNodeId3);

   InitializeBridge();
   StartSyncing();

   ASSERT_THAT(GetData(header_storage_key),
               EntityDataHasSpecifics(MatchesHeader(
                   kLocalCacheGuid, {kWindowId1}, {kTabId1, kTabId2})));

   // Close |kTabId2| and force reassociation by navigating in the remaining open
   // tab, leading to a freed tab entity.
   CloseTab(kTabId2);
   tab1->Navigate("http://foo2.com/");

   ASSERT_THAT(GetData(header_storage_key),
               EntityDataHasSpecifics(
                   MatchesHeader(kLocalCacheGuid, {kWindowId1}, {kTabId1})));

   ShutdownBridge();
   ResetWindows();

   // The browser gets restarted with a new initial tab, for example because the
   // user chose "Continue where you left off".
   AddWindow(kWindowId2);
   AddTab(kWindowId2, "http://baz.com/", kTabId3);

   // Start the bridge again.
   InitializeBridge();
   StartSyncing();

   // Two tab nodes should be free at this point, because both tabs have been
   // closed. However, they are also unsynced (the commit hasn't completed),
   // which prevents their recycling, so a new tab node should be created.
   ASSERT_THAT(
       GetAllData(),
       UnorderedElementsAre(
           Pair(header_storage_key,
                EntityDataHasSpecifics(
                    MatchesHeader(kLocalCacheGuid, {kWindowId2}, {kTabId3}))),
           Pair(tab_storage_key1,
                EntityDataHasSpecifics(
                    MatchesTab(kLocalCacheGuid, kWindowId1, kTabId1, kTabNodeId1,
                               {"http://foo.com/", "http://foo2.com/"}))),
           Pair(tab_storage_key2, EntityDataHasSpecifics(MatchesTab(
                                      kLocalCacheGuid, kWindowId1, kTabId2,
                                      kTabNodeId2, {"http://bar.com/"}))),
           Pair(tab_storage_key3, EntityDataHasSpecifics(MatchesTab(
                                      kLocalCacheGuid, kWindowId2, kTabId3,
                                      kTabNodeId3, {"http://baz.com/"})))));
 }

 TEST_F(SessionSyncBridgeTest, ShouldDisableSyncAndReenable) {
   const int kWindowId = 1000001;
   const int kTabId = 1000002;

   AddWindow(kWindowId);
   AddTab(kWindowId, "http://foo.com/", kTabId);

   InitializeBridge();
   StartSyncing();

   const std::string header_storage_key =
       SessionStore::GetHeaderStorageKey(kLocalCacheGuid);
   ASSERT_THAT(GetData(header_storage_key),
               EntityDataHasSpecifics(
                   MatchesHeader(kLocalCacheGuid, {kWindowId}, {kTabId})));
   ASSERT_THAT(GetAllData(), Not(IsEmpty()));

   EXPECT_CALL(mock_processor(), ModelReadyToSync).Times(0);
   real_processor()->OnSyncStopping(syncer::CLEAR_METADATA);

   StartSyncing();
   ASSERT_THAT(GetData(header_storage_key),
               EntityDataHasSpecifics(
                   MatchesHeader(kLocalCacheGuid, {kWindowId}, {kTabId})));
 }

 // Starting sync with no local data should just store the foreign entities in
 // the store and expose them via OpenTabsUIDelegate.
 TEST_F(SessionSyncBridgeTest, ShouldMergeForeignSession) {
   const std::string kForeignSessionTag = "foreignsessiontag";
   const int kForeignWindowId = 2000001;
   const int kForeignTabId = 2000002;
   const int kForeignTabNodeId = 2003;

   EXPECT_CALL(mock_processor(), UpdateStorageKey).Times(0);
   EXPECT_CALL(mock_processor(), Put).Times(0);
   InitializeBridge();

   const sync_pb::SessionSpecifics foreign_header =
       CreateHeaderSpecificsWithOneTab(kForeignSessionTag, kForeignWindowId,
                                       kForeignTabId);
   const sync_pb::SessionSpecifics foreign_tab =
       CreateTabSpecifics(kForeignSessionTag, kForeignWindowId, kForeignTabId,
                          kForeignTabNodeId, "http://baz.com/");

   EXPECT_CALL(
       mock_processor(),
       Put(_, EntityDataHasSpecifics(MatchesHeader(kLocalCacheGuid, _, _)), _));
   EXPECT_CALL(mock_foreign_session_updated_cb(), Run()).Times(AtLeast(1));
   StartSyncing({foreign_header, foreign_tab});

   std::vector<raw_ptr<const SyncedSession, VectorExperimental>>
       foreign_sessions;
   EXPECT_TRUE(bridge()->GetOpenTabsUIDelegate()->GetAllForeignSessions(
       &foreign_sessions));
   EXPECT_THAT(foreign_sessions,
               ElementsAre(MatchesSyncedSession(
                   kForeignSessionTag,
                   {{kForeignWindowId, std::vector<int>{kForeignTabId}}})));
 }

 // Starting sync even without remote data should trigger a notification for
 // updated foreign session.
 TEST_F(SessionSyncBridgeTest, ShouldTriggerNotificationWithoutRemoteData) {
   InitializeBridge();
   ASSERT_THAT(bridge()->GetOpenTabsUIDelegate(), IsNull());
   // Starting sync, even without remote data, should trigger a notification that
   // foreign sessions got updated, because `GetOpenTabsUIDelegate()`'s behavior
   // changed and it no longer returns null.
   EXPECT_CALL(mock_foreign_session_updated_cb(), Run());
   StartSyncing();

   EXPECT_THAT(bridge()->GetOpenTabsUIDelegate(), NotNull());
 }

 TEST_F(SessionSyncBridgeTest, ShouldNotExposeForeignHeaderWithoutTabs) {
   const std::string kForeignSessionTag = "foreignsessiontag";
   const int kForeignWindowId = 2000001;
   const int kForeignTabId = 2000002;

   EXPECT_CALL(mock_processor(), UpdateStorageKey).Times(0);
   EXPECT_CALL(mock_processor(), Put).Times(0);
   InitializeBridge();

   const sync_pb::SessionSpecifics foreign_header =
       CreateHeaderSpecificsWithOneTab(kForeignSessionTag, kForeignWindowId,
                                       kForeignTabId);
   const std::string foreign_header_storage_key =
       SessionStore::GetHeaderStorageKey(kForeignSessionTag);

   EXPECT_CALL(
       mock_processor(),
       Put(_, EntityDataHasSpecifics(MatchesHeader(kLocalCacheGuid, _, _)), _));

   StartSyncing({foreign_header});
   ASSERT_THAT(GetData(foreign_header_storage_key), NotNull());

   std::vector<raw_ptr<const SyncedSession, VectorExperimental>>
       foreign_sessions;
   EXPECT_FALSE(bridge()->GetOpenTabsUIDelegate()->GetAllForeignSessions(
       &foreign_sessions));

   // Restart bridge to verify the state doesn't change.
   ShutdownBridge();
   InitializeBridge();
   StartSyncing();
   ASSERT_THAT(GetData(foreign_header_storage_key), NotNull());

   EXPECT_FALSE(bridge()->GetOpenTabsUIDelegate()->GetAllForeignSessions(
       &foreign_sessions));
 }

 // Regression test for crbug.com/837517: Ensure that the bridge doesn't crash
 // and closed foreign tabs (|kForeignTabId2| in the test) are not exposed after
 // restarting the browser.
 TEST_F(SessionSyncBridgeTest, ShouldNotExposeClosedTabsAfterRestart) {
   const std::string kForeignSessionTag = "foreignsessiontag";
   const int kForeignWindowId = 2000001;
   const int kForeignTabId1 = 2000002;
   const int kForeignTabId2 = 2000003;
   const int kForeignTabNodeId1 = 2004;
   const int kForeignTabNodeId2 = 2005;

   // The header only lists a single tab |kForeignTabId1|, which becomes a mapped
   // tab.
   const sync_pb::SessionSpecifics foreign_header =
       CreateHeaderSpecificsWithOneTab(kForeignSessionTag, kForeignWindowId,
                                       kForeignTabId1);
   const sync_pb::SessionSpecifics foreign_tab1 =
       CreateTabSpecifics(kForeignSessionTag, kForeignWindowId, kForeignTabId1,
                          kForeignTabNodeId1, "http://foo.com/");
   // |kForeignTabId2| is not present in the header, leading to an unmapped tab.
   const sync_pb::SessionSpecifics foreign_tab2 =
       CreateTabSpecifics(kForeignSessionTag, kForeignWindowId, kForeignTabId2,
                          kForeignTabNodeId2, "http://bar.com/");

   InitializeBridge();
   StartSyncing({foreign_header, foreign_tab1, foreign_tab2});

   const std::string local_header_storage_key =
       SessionStore::GetHeaderStorageKey(kLocalCacheGuid);
   const std::string foreign_header_storage_key =
       SessionStore::GetHeaderStorageKey(kForeignSessionTag);
   const std::string foreign_tab_storage_key1 =
       SessionStore::GetTabStorageKey(kForeignSessionTag, kForeignTabNodeId1);
   const std::string foreign_tab_storage_key2 =
       SessionStore::GetTabStorageKey(kForeignSessionTag, kForeignTabNodeId2);

   ASSERT_THAT(
       GetAllData(),
       UnorderedElementsAre(
           Pair(local_header_storage_key, _),
           Pair(foreign_header_storage_key,
                EntityDataHasSpecifics(MatchesHeader(
                    kForeignSessionTag, {kForeignWindowId}, {kForeignTabId1}))),
           Pair(foreign_tab_storage_key1,
                EntityDataHasSpecifics(MatchesTab(
                    kForeignSessionTag, kForeignWindowId, kForeignTabId1,
                    kForeignTabNodeId1, {"http://foo.com/"}))),
           Pair(foreign_tab_storage_key2,
                EntityDataHasSpecifics(MatchesTab(
                    kForeignSessionTag, kForeignWindowId, kForeignTabId2,
                    kForeignTabNodeId2, {"http://bar.com/"})))));

   // Mimic a browser restart, which should restore the very same state (and not
   // crash!).
   ShutdownBridge();
   InitializeBridge();
   StartSyncing();

   EXPECT_THAT(GetAllData(),
               UnorderedElementsAre(Pair(local_header_storage_key, _),
                                    Pair(foreign_header_storage_key, _),
                                    Pair(foreign_tab_storage_key1, _),
                                    Pair(foreign_tab_storage_key2, _)));
 }

 TEST_F(SessionSyncBridgeTest, ShouldHandleRemoteDeletion) {
   const std::string kForeignSessionTag = "foreignsessiontag";
   const int kForeignWindowId = 2000001;
   const int kForeignTabId = 2000002;
   const int kForeignTabNodeId = 2003;

   InitializeBridge();

   const sync_pb::SessionSpecifics foreign_header =
       CreateHeaderSpecificsWithOneTab(kForeignSessionTag, kForeignWindowId,
                                       kForeignTabId);
   const sync_pb::SessionSpecifics foreign_tab =
       CreateTabSpecifics(kForeignSessionTag, kForeignWindowId, kForeignTabId,
                          kForeignTabNodeId, "http://baz.com/");
   StartSyncing({foreign_header, foreign_tab});

   // Mimic receiving a commit ack for the local header entity, to later be able
   // to verify HasLocalChangesForTest() without interferences from the local
   // session.
   ASSERT_TRUE(real_processor()->HasLocalChangesForTest());
   real_processor()->OnCommitCompleted(
       GetModelTypeStateWithInitialSyncDone(),
       {CreateSuccessResponse(kLocalCacheGuid)},
       /*error_response_list=*/FailedCommitResponseDataList());
   ASSERT_FALSE(real_processor()->HasLocalChangesForTest());

   const sessions::SessionTab* foreign_session_tab = nullptr;
   ASSERT_TRUE(bridge()->GetOpenTabsUIDelegate()->GetForeignTab(
       kForeignSessionTag, SessionID::FromSerializedValue(kForeignTabId),
       &foreign_session_tab));
   ASSERT_THAT(foreign_session_tab, NotNull());
   std::vector<raw_ptr<const SyncedSession, VectorExperimental>>
       foreign_sessions;
   ASSERT_TRUE(bridge()->GetOpenTabsUIDelegate()->GetAllForeignSessions(
       &foreign_sessions));
   ASSERT_THAT(foreign_sessions,
               ElementsAre(MatchesSyncedSession(
                   kForeignSessionTag,
                   {{kForeignWindowId, std::vector<int>{kForeignTabId}}})));
   ASSERT_TRUE(real_processor()->IsTrackingMetadata());
   ASSERT_TRUE(real_processor()->IsTrackingEntityForTest(
       SessionStore::GetHeaderStorageKey(kForeignSessionTag)));
   ASSERT_TRUE(real_processor()->IsTrackingEntityForTest(
       SessionStore::GetTabStorageKey(kForeignSessionTag, kForeignTabNodeId)));
   ASSERT_FALSE(real_processor()->HasLocalChangesForTest());

   // Mimic receiving a remote deletion of the foreign session.
   EXPECT_CALL(mock_foreign_session_updated_cb(), Run());
   syncer::UpdateResponseDataList updates;
   updates.push_back(
       CreateTombstone(SessionStore::GetClientTag(foreign_header)));
   real_processor()->OnUpdateReceived(GetModelTypeStateWithInitialSyncDone(),
                                      std::move(updates),
                                      /*gc_directive=*/std::nullopt);

   foreign_session_tab = nullptr;
   EXPECT_FALSE(bridge()->GetOpenTabsUIDelegate()->GetForeignTab(
       kForeignSessionTag, SessionID::FromSerializedValue(kForeignTabId),
       &foreign_session_tab));

   EXPECT_FALSE(bridge()->GetOpenTabsUIDelegate()->GetAllForeignSessions(
       &foreign_sessions));

   EXPECT_FALSE(real_processor()->HasLocalChangesForTest());

   const std::string header_storage_key =
       SessionStore::GetHeaderStorageKey(kForeignSessionTag);
   const std::string tab_storage_key =
       SessionStore::GetTabStorageKey(kForeignSessionTag, kForeignTabNodeId);

   EXPECT_FALSE(real_processor()->IsTrackingEntityForTest(header_storage_key));
   EXPECT_FALSE(real_processor()->IsTrackingEntityForTest(tab_storage_key));

   // Verify that both entities have been deleted from storage.
   {
     base::RunLoop loop;
     underlying_store()->ReadData(
         {header_storage_key, tab_storage_key},
         base::BindLambdaForTesting(
             [&](const std::optional<syncer::ModelError>& error,
                 std::unique_ptr<syncer::ModelTypeStore::RecordList>
                     data_records,
                 std::unique_ptr<syncer::ModelTypeStore::IdList>
                     missing_id_list) {
               EXPECT_THAT(data_records, Pointee(IsEmpty()));
               EXPECT_THAT(
                   missing_id_list,
                   Pointee(ElementsAre(header_storage_key, tab_storage_key)));
               loop.Quit();
             }));
     loop.Run();
   }

   // Verify that the sync metadata for both entities have been deleted too.
   {
     base::RunLoop loop;
     underlying_store()->ReadAllMetadata(base::BindLambdaForTesting(
         [&](const std::optional<syncer::ModelError>& error,
             std::unique_ptr<syncer::MetadataBatch> metadata_batch) {
           syncer::EntityMetadataMap entity_metadata_map =
               metadata_batch->TakeAllMetadata();
           EXPECT_EQ(0U, entity_metadata_map.count(header_storage_key));
           EXPECT_EQ(0U, entity_metadata_map.count(tab_storage_key));
           loop.Quit();
         }));
     loop.Run();
   }
 }

 TEST_F(SessionSyncBridgeTest, ShouldIgnoreRemoteDeletionOfLocalTab) {
   const int kWindowId1 = 1000001;
   const int kTabId1 = 1000002;
   const int kTabNodeId1 = 0;

   AddWindow(kWindowId1);
   AddTab(kWindowId1, "http://foo.com/", kTabId1);

   InitializeBridge();
   StartSyncing();

   const std::string header_storage_key =
       SessionStore::GetHeaderStorageKey(kLocalCacheGuid);
   const std::string tab_storage_key1 =
       SessionStore::GetTabStorageKey(kLocalCacheGuid, kTabNodeId1);
   const std::string tab_client_tag1 =
       SessionStore::GetTabClientTagForTest(kLocalCacheGuid, kTabNodeId1);

   ASSERT_THAT(
       GetAllData(),
       UnorderedElementsAre(
           Pair(header_storage_key,
                EntityDataHasSpecifics(MatchesHeader(kLocalCacheGuid, _, _))),
           Pair(tab_storage_key1, EntityDataHasSpecifics(MatchesTab(
                                      kLocalCacheGuid, kWindowId1, kTabId1,
                                      kTabNodeId1, {"http://foo.com/"})))));
   ASSERT_TRUE(real_processor()->IsTrackingMetadata());
   ASSERT_TRUE(real_processor()->HasLocalChangesForTest());

   // Mimic receiving a commit ack for both the tab and the header entity,
   // because otherwise it will be treated as conflict, and then local wins.
   real_processor()->OnCommitCompleted(
       GetModelTypeStateWithInitialSyncDone(),
       {CreateSuccessResponse(tab_client_tag1),
        CreateSuccessResponse(kLocalCacheGuid)},
       /*error_response_list=*/FailedCommitResponseDataList());
   ASSERT_FALSE(real_processor()->HasLocalChangesForTest());

   // Mimic receiving a remote deletion of both entities.
   ASSERT_FALSE(bridge()->IsLocalDataOutOfSyncForTest());
   EXPECT_CALL(mock_processor(), Put).Times(0);
   syncer::UpdateResponseDataList updates;
   updates.push_back(CreateTombstone(kLocalCacheGuid));
   updates.push_back(CreateTombstone(tab_client_tag1));
   real_processor()->OnUpdateReceived(GetModelTypeStateWithInitialSyncDone(),
                                      std::move(updates),
                                      /*gc_directive=*/std::nullopt);

   // State should remain unchanged (deletions ignored).
   EXPECT_TRUE(bridge()->IsLocalDataOutOfSyncForTest());
   EXPECT_THAT(
       GetAllData(),
       UnorderedElementsAre(
           Pair(header_storage_key,
                EntityDataHasSpecifics(MatchesHeader(kLocalCacheGuid, _, _))),
           Pair(tab_storage_key1, EntityDataHasSpecifics(MatchesTab(
                                      kLocalCacheGuid, kWindowId1, kTabId1,
                                      kTabNodeId1, {"http://foo.com/"})))));

   // Creating a new tab locally should trigger Put() calls for *all* entities
   // (because the local data was out of sync).
   const int kWindowId2 = 2000001;
   const int kTabId2 = 2000002;
   const int kTabNodeId2 = 1;

   const std::string tab_storage_key2 =
       SessionStore::GetTabStorageKey(kLocalCacheGuid, kTabNodeId2);

   // Window creation already triggers a header update, which will be overriden
   // later below.
   testing::Expectation put_transient_header =
       EXPECT_CALL(mock_processor(), Put(header_storage_key, _, _));
   AddWindow(kWindowId2);

   // In the current implementation, some of the updates are reported to the
   // processor twice, but that's OK because the processor can detect it.
   EXPECT_CALL(mock_processor(),
               Put(header_storage_key,
                   EntityDataHasSpecifics(MatchesHeader(
                       kLocalCacheGuid, ElementsAre(kWindowId1, kWindowId2),
                       ElementsAre(kTabId1, kTabId2))),
                   _))
       .Times(2)
       .After(put_transient_header);
   EXPECT_CALL(mock_processor(), Put(tab_storage_key1,
                                     EntityDataHasSpecifics(MatchesTab(
                                         kLocalCacheGuid, kWindowId1, kTabId1,
                                         kTabNodeId1, {"http://foo.com/"})),
                                     _));
   EXPECT_CALL(mock_processor(), Put(tab_storage_key2,
                                     EntityDataHasSpecifics(MatchesTab(
                                         kLocalCacheGuid, kWindowId2, kTabId2,
                                         kTabNodeId2, {"http://bar.com/"})),
                                     _))
       .Times(2);

   AddTab(kWindowId2, "http://bar.com/", kTabId2);

   EXPECT_THAT(
       GetAllData(),
       UnorderedElementsAre(
           Pair(header_storage_key,
                EntityDataHasSpecifics(MatchesHeader(
                    kLocalCacheGuid, ElementsAre(kWindowId1, kWindowId2),
                    ElementsAre(kTabId1, kTabId2)))),
           Pair(tab_storage_key1,
                EntityDataHasSpecifics(
                    MatchesTab(kLocalCacheGuid, /*window_id=*/_, /*tab_id=*/_,
                               kTabNodeId1, {"http://foo.com/"}))),
           Pair(tab_storage_key2, EntityDataHasSpecifics(MatchesTab(
                                      kLocalCacheGuid, kWindowId2, kTabId2,
                                      kTabNodeId2, {"http://bar.com/"})))));

   // Run until idle because PostTask() is used to invoke ResubmitLocalSession().
   base::RunLoop().RunUntilIdle();
 }

 // Test that remote deletion of local data will not result in a placeholder tab
 // being lost.
 TEST_F(SessionSyncBridgeTest, ShouldIgnoreRemoteDeletionOfLocalPlaceholderTab) {
   const int kWindowId1 = 1000001;
   const int kTabId1 = 1000003;
   // Zero is the first assigned tab node ID.
   const int kTabNodeId1 = 0;

   AddWindow(kWindowId1);
   AddTab(kWindowId1, "http://foo.com/", kTabId1);

   InitializeBridge();
   StartSyncing();

   const std::string header_storage_key =
       SessionStore::GetHeaderStorageKey(kLocalCacheGuid);
   const std::string tab_storage_key1 =
       SessionStore::GetTabStorageKey(kLocalCacheGuid, kTabNodeId1);
   const std::string tab_client_tag1 =
       SessionStore::GetTabClientTagForTest(kLocalCacheGuid, kTabNodeId1);

   ASSERT_THAT(
       GetAllData(),
       UnorderedElementsAre(
           Pair(header_storage_key,
                EntityDataHasSpecifics(MatchesHeader(kLocalCacheGuid, _, _))),
           Pair(tab_storage_key1, EntityDataHasSpecifics(MatchesTab(
                                      kLocalCacheGuid, kWindowId1, kTabId1,
                                      kTabNodeId1, {"http://foo.com/"})))));

   ASSERT_TRUE(real_processor()->HasLocalChangesForTest());

   // Mimic receiving a commit ack for both the tab and the header entity,
   // because otherwise it will be treated as conflict, and then local wins.
   real_processor()->OnCommitCompleted(
       GetModelTypeStateWithInitialSyncDone(),
       {CreateSuccessResponse(tab_client_tag1),
        CreateSuccessResponse(kLocalCacheGuid)},
       /*error_response_list=*/FailedCommitResponseDataList());
   ASSERT_FALSE(real_processor()->HasLocalChangesForTest());

   ShutdownBridge();

   // Override the tab with a placeholder tab delegate. Note that, on Android,
   // tab IDs are persisted by session restore across browser restarts.
   PlaceholderTabDelegate placeholder_tab1(
       SessionID::FromSerializedValue(kTabId1));
   ResetWindows();
   TestSyncedWindowDelegate* window = AddWindow(kWindowId1);
   window->OverrideTabAt(0, &placeholder_tab1);

   // Start the bridge again.
   InitializeBridge();
   StartSyncing();
   ASSERT_TRUE(real_processor()->IsTrackingMetadata());
   ASSERT_FALSE(real_processor()->HasLocalChangesForTest());

   // Mimic receiving a remote deletion of both entities (header and tab).
   ASSERT_FALSE(bridge()->IsLocalDataOutOfSyncForTest());
   syncer::UpdateResponseDataList updates;
   updates.push_back(CreateTombstone(kLocalCacheGuid));
   updates.push_back(CreateTombstone(tab_client_tag1));
   real_processor()->OnUpdateReceived(GetModelTypeStateWithInitialSyncDone(),
                                      std::move(updates),
                                      /*gc_directive=*/std::nullopt);

   // State should remain unchanged (deletions ignored), but the local data
   // should be marked as "out of sync".
   EXPECT_TRUE(bridge()->IsLocalDataOutOfSyncForTest());
   EXPECT_THAT(
       GetAllData(),
       UnorderedElementsAre(
           Pair(header_storage_key,
                EntityDataHasSpecifics(MatchesHeader(kLocalCacheGuid, _, _))),
           Pair(tab_storage_key1, EntityDataHasSpecifics(MatchesTab(
                                      kLocalCacheGuid, kWindowId1, kTabId1,
                                      kTabNodeId1, {"http://foo.com/"})))));

   ShutdownBridge();

   // Start the bridge once again. The state should remain unchanged.
   InitializeBridge();
   EXPECT_TRUE(bridge()->IsLocalDataOutOfSyncForTest());
   StartSyncing();
   EXPECT_THAT(
       GetAllData(),
       UnorderedElementsAre(
           Pair(header_storage_key,
                EntityDataHasSpecifics(MatchesHeader(kLocalCacheGuid, _, _))),
           Pair(tab_storage_key1, EntityDataHasSpecifics(MatchesTab(
                                      kLocalCacheGuid, kWindowId1, kTabId1,
                                      kTabNodeId1, {"http://foo.com/"})))));

   // ResubmitLocalSession() should have been posted and the LocalDataOutOfSync
   // state cleared. However, the data has not yet been sent to the processor.
   EXPECT_FALSE(bridge()->IsLocalDataOutOfSyncForTest());
   ASSERT_FALSE(real_processor()->HasLocalChangesForTest());

   // Run until idle because PostTask() is used to invoke ResubmitLocalSession().
   base::RunLoop().RunUntilIdle();

   // The local data should have been sent for reupload, but no commit has
   // occurred yet.
   ASSERT_TRUE(real_processor()->HasLocalChangesForTest());
 }

 // Test that while remote deletion will not delete data, local metadata deletion
 // from an action such as toggling sync will properly delete metadata and not
 // reupload it.
 TEST_F(SessionSyncBridgeTest, ShouldNotRestoreLocalSessionWithoutMetadata) {
   const int kWindowId1 = 1000001;
   const int kTabId1 = 1000003;
   const int kTabId2 = 1000004;
   // Zero is the first assigned tab node ID.
   const int kTabNodeId1 = 0;
   const int kTabNodeId2 = 1;

   AddWindow(kWindowId1);
   AddTab(kWindowId1, "http://foo.com/", kTabId1);
   AddTab(kWindowId1, "http://bar.com/", kTabId2);

   InitializeBridge();
   StartSyncing();

   const std::string header_storage_key =
       SessionStore::GetHeaderStorageKey(kLocalCacheGuid);
   const std::string tab_storage_key1 =
       SessionStore::GetTabStorageKey(kLocalCacheGuid, kTabNodeId1);
   const std::string tab_client_tag1 =
       SessionStore::GetTabClientTagForTest(kLocalCacheGuid, kTabNodeId1);
   const std::string tab_storage_key2 =
       SessionStore::GetTabStorageKey(kLocalCacheGuid, kTabNodeId2);
   const std::string tab_client_tag2 =
       SessionStore::GetTabClientTagForTest(kLocalCacheGuid, kTabNodeId2);

   ASSERT_THAT(
       GetAllData(),
       UnorderedElementsAre(
           Pair(header_storage_key,
                EntityDataHasSpecifics(MatchesHeader(kLocalCacheGuid, _, _))),
           Pair(tab_storage_key1, EntityDataHasSpecifics(MatchesTab(
                                      kLocalCacheGuid, kWindowId1, kTabId1,
                                      kTabNodeId1, {"http://foo.com/"}))),
           Pair(tab_storage_key2, EntityDataHasSpecifics(MatchesTab(
                                      kLocalCacheGuid, kWindowId1, kTabId2,
                                      kTabNodeId2, {"http://bar.com/"})))));

   ASSERT_TRUE(real_processor()->HasLocalChangesForTest());

   // Mimic receiving a commit ack for both the tabs and the header entity,
   // because otherwise it will be treated as conflict, and then local wins.
   real_processor()->OnCommitCompleted(
       GetModelTypeStateWithInitialSyncDone(),
       {CreateSuccessResponse(tab_client_tag1),
        CreateSuccessResponse(tab_client_tag2),
        CreateSuccessResponse(kLocalCacheGuid)},
       /*error_response_list=*/FailedCommitResponseDataList());

   ASSERT_FALSE(real_processor()->HasLocalChangesForTest());
   ASSERT_TRUE(real_processor()->IsTrackingMetadata());

   // Mimic receiving a remote deletion of all entities.
   ASSERT_FALSE(bridge()->IsLocalDataOutOfSyncForTest());
   syncer::UpdateResponseDataList updates;
   updates.push_back(CreateTombstone(kLocalCacheGuid));
   updates.push_back(CreateTombstone(tab_client_tag1));
   updates.push_back(CreateTombstone(tab_client_tag2));
   real_processor()->OnUpdateReceived(GetModelTypeStateWithInitialSyncDone(),
                                      std::move(updates),
                                      /*gc_directive=*/std::nullopt);

   // State should remain unchanged (deletions ignored).
   EXPECT_TRUE(bridge()->IsLocalDataOutOfSyncForTest());
   EXPECT_THAT(
       GetAllData(),
       UnorderedElementsAre(
           Pair(header_storage_key,
                EntityDataHasSpecifics(MatchesHeader(kLocalCacheGuid, _, _))),
           Pair(tab_storage_key1, EntityDataHasSpecifics(MatchesTab(
                                      kLocalCacheGuid, kWindowId1, kTabId1,
                                      kTabNodeId1, {"http://foo.com/"}))),
           Pair(tab_storage_key2, EntityDataHasSpecifics(MatchesTab(
                                      kLocalCacheGuid, kWindowId1, kTabId2,
                                      kTabNodeId2, {"http://bar.com/"})))));

   ShutdownBridge();

   // Override tab1 with a placeholder tab delegate. Note that, on Android,
   // tab IDs are persisted by session restore across browser restarts.
   PlaceholderTabDelegate placeholder_tab1(
       SessionID::FromSerializedValue(kTabId1));
   auto snapshot1 = std::make_unique<TestSyncedTabDelegate>(
       SessionID::FromSerializedValue(kWindowId1),
       SessionID::FromSerializedValue(kTabId1), base::DoNothing());
   placeholder_tab1.SetPlaceholderTabSyncedTabDelegate(std::move(snapshot1));

   ResetWindows();
   TestSyncedWindowDelegate* window = AddWindow(kWindowId1);
   window->OverrideTabAt(0, &placeholder_tab1);
   AddTab(kWindowId1, "http://bar.com/", kTabId2);

   // Start the bridge again.
   InitializeBridge();

   // Clear the metadata. This will lose the placeholder tab permanently.
   real_processor()->ClearMetadataIfStopped();
   EXPECT_TRUE(bridge()->IsLocalDataOutOfSyncForTest());

   StartSyncing();
   ASSERT_TRUE(real_processor()->IsTrackingMetadata());

   // The TabNodeId gets re-used now that tab1 is gone.
   const std::string tab_storage_key2_reused =
       SessionStore::GetTabStorageKey(kLocalCacheGuid, kTabNodeId1);
   const std::string tab_client_tag2_reused =
       SessionStore::GetTabClientTagForTest(kLocalCacheGuid, kTabNodeId1);

   // The header and non-placeholder tab should both be restored, but the
   // placeholder tab got lost.
   // TODO(crbug/1462305): on Android it should be possible to reupload
   // placeholder tabs.
   EXPECT_FALSE(bridge()->IsLocalDataOutOfSyncForTest());
   EXPECT_THAT(GetAllData(),
               UnorderedElementsAre(
                   Pair(header_storage_key, EntityDataHasSpecifics(MatchesHeader(
                                                kLocalCacheGuid, _, _))),
                   Pair(tab_storage_key2_reused,
                        EntityDataHasSpecifics(
                            MatchesTab(kLocalCacheGuid, kWindowId1, kTabId2,
                                       kTabNodeId1, {"http://bar.com/"})))));
 }

 // Verifies that a foreign session can be deleted by the user from the history
 // UI (via OpenTabsUIDelegate).
 TEST_F(SessionSyncBridgeTest, ShouldDeleteForeignSessionFromUI) {
   const std::string kForeignSessionTag = "foreignsessiontag";
   const int kForeignWindowId = 2000001;
   const int kForeignTabId = 2000002;
   const int kForeignTabNodeId = 2003;

   InitializeBridge();

   const sync_pb::SessionSpecifics foreign_header =
       CreateHeaderSpecificsWithOneTab(kForeignSessionTag, kForeignWindowId,
                                       kForeignTabId);
   const sync_pb::SessionSpecifics foreign_tab =
       CreateTabSpecifics(kForeignSessionTag, kForeignWindowId, kForeignTabId,
                          kForeignTabNodeId, "http://baz.com/");
   StartSyncing({foreign_header, foreign_tab});

   const std::string foreign_header_storage_key =
       SessionStore::GetHeaderStorageKey(kForeignSessionTag);
   const std::string foreign_tab_storage_key =
       SessionStore::GetTabStorageKey(kForeignSessionTag, kForeignTabNodeId);

   // Test fixture expects the two foreign entities in the model as well as the
   // underlying store.
   ASSERT_THAT(GetData(foreign_header_storage_key), NotNull());
   ASSERT_THAT(GetData(foreign_tab_storage_key), NotNull());

   const sessions::SessionTab* foreign_session_tab = nullptr;
   ASSERT_TRUE(bridge()->GetOpenTabsUIDelegate()->GetForeignTab(
       kForeignSessionTag, SessionID::FromSerializedValue(kForeignTabId),
       &foreign_session_tab));
   ASSERT_THAT(foreign_session_tab, NotNull());
   std::vector<raw_ptr<const SyncedSession, VectorExperimental>>
       foreign_sessions;
   ASSERT_TRUE(bridge()->GetOpenTabsUIDelegate()->GetAllForeignSessions(
       &foreign_sessions));
   ASSERT_THAT(foreign_sessions,
               ElementsAre(MatchesSyncedSession(
                   kForeignSessionTag,
                   {{kForeignWindowId, std::vector<int>{kForeignTabId}}})));
   ASSERT_TRUE(real_processor()->IsTrackingMetadata());

   // Mimic the user requesting a session deletion from the UI.
   EXPECT_CALL(mock_processor(), Delete(foreign_header_storage_key, _));
   EXPECT_CALL(mock_processor(), Delete(foreign_tab_storage_key, _));
   EXPECT_CALL(mock_foreign_session_updated_cb(), Run());
   bridge()->GetOpenTabsUIDelegate()->DeleteForeignSession(kForeignSessionTag);

   // Verify what gets exposed to the UI.
   foreign_session_tab = nullptr;
   EXPECT_FALSE(bridge()->GetOpenTabsUIDelegate()->GetForeignTab(
       kForeignSessionTag, SessionID::FromSerializedValue(kForeignTabId),
       &foreign_session_tab));
   EXPECT_FALSE(bridge()->GetOpenTabsUIDelegate()->GetAllForeignSessions(
       &foreign_sessions));

   // Verify store.
   EXPECT_THAT(GetData(foreign_header_storage_key), IsNull());
   EXPECT_THAT(GetData(foreign_tab_storage_key), IsNull());
 }

 // Verifies that attempts to delete the local session from the UI are ignored,
 // although the UI sholdn't really be offering that option.
 TEST_F(SessionSyncBridgeTest, ShouldIgnoreLocalSessionDeletionFromUI) {
   InitializeBridge();
   StartSyncing();

   EXPECT_CALL(mock_foreign_session_updated_cb(), Run()).Times(0);
   EXPECT_CALL(mock_processor(), Delete).Times(0);

   bridge()->GetOpenTabsUIDelegate()->DeleteForeignSession(kLocalCacheGuid);

   const SyncedSession* session = nullptr;
   EXPECT_TRUE(bridge()->GetOpenTabsUIDelegate()->GetLocalSession(&session));
   EXPECT_THAT(session, NotNull());
   EXPECT_THAT(GetData(SessionStore::GetHeaderStorageKey(kLocalCacheGuid)),
               NotNull());
 }

 // Verifies that receiving an empty update list does not broadcast a foreign
 // session change via the corresponding callback.
 TEST_F(SessionSyncBridgeTest, ShouldNotBroadcastUpdatesIfEmpty) {
   InitializeBridge();
   StartSyncing();

   EXPECT_CALL(mock_foreign_session_updated_cb(), Run()).Times(0);

   // Mimic receiving an empty list of remote updates.
   real_processor()->OnUpdateReceived(GetModelTypeStateWithInitialSyncDone(), {},
                                      /*gc_directive=*/std::nullopt);
 }

 TEST_F(SessionSyncBridgeTest, ShouldDoGarbageCollection) {
   // We construct two identical sessions, one modified recently, one modified
   // more than |kStaleSessionThreshold| ago (28 days ago).
   const base::Time stale_mtime = base::Time::Now() - base::Days(29);
   const base::Time recent_mtime = base::Time::Now() - base::Days(27);
   const std::string kStaleSessionTag = "stalesessiontag";
   const std::string kRecentSessionTag = "recentsessiontag";
   const int kWindowId = 2000001;
   const int kTabId = 2000002;
   const int kTabNodeId = 2003;

   InitializeBridge();
   StartSyncing();

   // Construct a remote update.
   syncer::UpdateResponseDataList updates;
   // Two entities belong to a recent session.
   updates.push_back(SpecificsToUpdateResponse(
       CreateHeaderSpecificsWithOneTab(kStaleSessionTag, kWindowId, kTabId),
       stale_mtime));
   updates.push_back(SpecificsToUpdateResponse(
       CreateTabSpecifics(kStaleSessionTag, kWindowId, kTabId, kTabNodeId,
                          "http://baz.com/"),
       stale_mtime));
   updates.push_back(SpecificsToUpdateResponse(
       CreateHeaderSpecificsWithOneTab(kRecentSessionTag, kWindowId, kTabId),
       recent_mtime));
   updates.push_back(SpecificsToUpdateResponse(
       CreateTabSpecifics(kRecentSessionTag, kWindowId, kTabId, kTabNodeId,
                          "http://baz.com/"),
       recent_mtime));

   // During garbage collection, we expect |kStaleSessionTag| to be deleted.
   EXPECT_CALL(mock_processor(),
               Delete(SessionStore::GetHeaderStorageKey(kStaleSessionTag), _));
   EXPECT_CALL(
       mock_processor(),
       Delete(SessionStore::GetTabStorageKey(kStaleSessionTag, kTabNodeId), _));

   EXPECT_CALL(mock_foreign_session_updated_cb(), Run()).Times(AtLeast(1));
   real_processor()->OnUpdateReceived(GetModelTypeStateWithInitialSyncDone(),
                                      std::move(updates),
                                      /*gc_directive=*/std::nullopt);
 }

 TEST_F(SessionSyncBridgeTest, ShouldReturnBrowserTypeInGetData) {
   const int kWindowId = 1000001;
   const int kTabId = 1000002;

   AddWindow(kWindowId, sync_pb::SyncEnums_BrowserType_TYPE_CUSTOM_TAB);
   AddTab(kWindowId, "http://foo.com/", kTabId);

   InitializeBridge();
   StartSyncing();

   std::unique_ptr<EntityData> tab_data = GetData(
       SessionStore::GetTabStorageKey(kLocalCacheGuid, /*tab_node_id=*/0));
   ASSERT_THAT(tab_data, NotNull());

   EXPECT_EQ(sync_pb::SyncEnums_BrowserType_TYPE_CUSTOM_TAB,
             tab_data->specifics.session().tab().browser_type());
 }

 }  // namespace
 }  // namespace sync_sessions