Remove ...LOADED_DEPRECATED and its friends

Use ExtensionRegistryObserver instead of NOTIFICATION_EXTENSION_LOADED_DEPRECATED
from ExtensionTestNotificationObserver.
Also, Remove ExtensionTestNotificationObserver::WaitForExtensionLoad()
since it has a possibility to catch unexpected extension's loaded
notification. Instead of that, use TestExtensionRegistryObserver.

BUG=411568
TEST=browser_tests

Review-Url: https://codereview.chromium.org/2753513006
Cr-Commit-Position: refs/heads/master@{#464703}

diff --git a/extensions/test/extension_test_notification_observer.h b/extensions/test/extension_test_notification_observer.h
index 418d567a..fe2aa8e 100644
--- a/extensions/test/extension_test_notification_observer.h
+++ b/extensions/test/extension_test_notification_observer.h

@@ -14,6 +14,7 @@
 #include "base/scoped_observer.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
+#include "extensions/browser/extension_registry_observer.h"
 #include "extensions/browser/process_manager_observer.h"
 
 namespace content {
@@ -23,10 +24,12 @@
 }
 
 namespace extensions {
+class ExtensionRegistry;
 class ProcessManager;
 
 // Test helper class for observing extension-related events.
-class ExtensionTestNotificationObserver : public content::NotificationObserver {
+class ExtensionTestNotificationObserver : public content::NotificationObserver,
+                                          ExtensionRegistryObserver {
  public:
   explicit ExtensionTestNotificationObserver(content::BrowserContext* context);
   ~ExtensionTestNotificationObserver() override;
@@ -35,9 +38,6 @@
   // error was raised.
   bool WaitForExtensionInstallError();
 
-  // Waits until an extension is loaded.
-  void WaitForExtensionLoad();
-
   // Waits for an extension load error. Returns true if the error really
   // happened.
   bool WaitForExtensionLoadError();
@@ -67,11 +67,16 @@
     last_loaded_extension_id_ = last_loaded_extension_id;
   }
 
-  // content::NotificationObserver
+  // content::NotificationObserver:
   void Observe(int type,
                const content::NotificationSource& source,
                const content::NotificationDetails& details) override;
 
+  // ExtensionRegistryObserver:
+  void OnExtensionLoaded(content::BrowserContext* browser_context,
+                         const Extension* extension) override;
+  void OnShutdown(ExtensionRegistry* registry) override;
+
  protected:
   class NotificationSet : public content::NotificationObserver,
                           public extensions::ProcessManagerObserver {
@@ -136,6 +141,10 @@
   // The closure to quit the currently-running message loop.
   base::Closure quit_closure_;
 
+  // Listens to extension loaded notifications.
+  ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
+      registry_observer_;
+
   DISALLOW_COPY_AND_ASSIGN(ExtensionTestNotificationObserver);
 };