Refactor media out of WebContentsImpl to MediaWebContentsObserver.

content/public/browser/web_contents_observer.h

 // Copyright (c) 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.
 
 #ifndef CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_OBSERVER_H_
 #define CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_OBSERVER_H_
 
 #include "base/process/kill.h"
 #include "base/process/process_handle.h"
 #include "content/common/content_export.h"
@@ skipping 406 matching lines @@
   // Invoked when a user cancels a before unload dialog.
   virtual void BeforeUnloadDialogCancelled() {}
 
   // Invoked when an accessibility event is received from the renderer process.
   virtual void AccessibilityEventReceived(
       const std::vector<AXEventNotificationDetails>& details) {}
 
   // Invoked when theme color is changed to |theme_color|.
   virtual void DidChangeThemeColor(SkColor theme_color) {}
 
-  // Invoked when media is playing.
-  virtual void MediaStartedPlaying() {}
-
-  // Invoked when media is paused.
-  virtual void MediaPaused() {}
+  // Invoked when media is playing or paused.  |id| is unique per player and per
+  // RenderFrameHost.  There may be multiple players within a RenderFrameHost
+  // and subsequently within a WebContents.  MediaStartedPlaying() will always
+  // be followed by MediaStoppedPlaying() after player teardown.  Observers must
+  // release all stored copies of |id| when MediaStoppedPlaying() is received.
+  using MediaPlayerId = std::pair<RenderFrameHost*, int64_t>;
+  virtual void MediaStartedPlaying(const MediaPlayerId& id) {}
+  virtual void MediaStoppedPlaying(const MediaPlayerId& id) {}
 
   // Invoked when media session has changed its state.
   virtual void MediaSessionStateChanged(bool is_controllable,
                                         bool is_suspended) {}
 
   // Invoked when the renderer process changes the page scale factor.
   virtual void OnPageScaleFactorChanged(float page_scale_factor) {}
 
   // Invoked if an IPC message is coming from a specific RenderFrameHost.
   virtual bool OnMessageReceived(const IPC::Message& message,
@@ skipping 32 matching lines @@
   void ResetWebContents();
 
   WebContentsImpl* web_contents_;
 
   DISALLOW_COPY_AND_ASSIGN(WebContentsObserver);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_OBSERVER_H_