Link MediaSessionTabHelper with native MediaSession [CL is going to be split]

content/public/android/java/src/org/chromium/content_public/browser/WebContentsObserver.java

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.content_public.browser;
 
-import org.chromium.content_public.common.MediaMetadata;
-
 import java.lang.ref.WeakReference;
 
 /**
  * This class receives callbacks that act as hooks for various a native web contents events related
  * to loading a url. A single web contents can have multiple WebContentObservers.
  */
 public abstract class WebContentsObserver {
     // TODO(jdduke): Remove the destroy method and hold observer embedders
     // responsible for explicit observer detachment.
     // Using a weak reference avoids cycles that might prevent GC of WebView's WebContents.
@@ skipping 137 matching lines @@
      */
     public void didChangeThemeColor(int color) {}
 
     /**
      * Called when we started navigation to the pending entry.
      * @param url        The URL that we are navigating to.
      */
     public void didStartNavigationToPendingEntry(String url) {}
 
     /**
-     * Called when the media session state changed.
-     * @param isControllable if the session can be resumed or suspended.
-     * @param isSuspended if the session currently suspended or not.
-     */
-    public void mediaSessionStateChanged(boolean isControllable, boolean isSuspended) {}
-
-    /**
-     * Called when the media session metadata changed.
-     * @param metadata the new MediaMetadata after change.
-     */
-    public void mediaSessionMetadataChanged(MediaMetadata metadata) {}
-
-    /**
      * Stop observing the web contents and clean up associated references.
      */
     public void destroy() {
         if (mWebContents == null) return;
         final WebContents webContents = mWebContents.get();
         mWebContents = null;
         if (webContents == null) return;
         webContents.removeObserver(this);
     }
 
     protected WebContentsObserver() {}
 }