Refactor media out of WebContentsImpl to MediaWebContentsObserver.

content/browser/media/media_web_contents_observer.h

Index: content/browser/media/media_web_contents_observer.h
diff --git a/content/browser/media/media_web_contents_observer.h b/content/browser/media/media_web_contents_observer.h
index 382dcdf772f63b00749b65918d4d87bcd3098028..fdba88394cb5b0246775fbc702a474514bd81cac 100644
--- a/content/browser/media/media_web_contents_observer.h
+++ b/content/browser/media/media_web_contents_observer.h
@@ -7,6 +7,7 @@
 
 #include "base/compiler_specific.h"
 #include "base/containers/scoped_ptr_hash_map.h"
+#include "content/browser/power_save_blocker_impl.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/web_contents_observer.h"
 
@@ -21,43 +22,104 @@ class BrowserMediaPlayerManager;
 // for sending IPCs back to the RenderFrameObservers at the render side.
 class CONTENT_EXPORT MediaWebContentsObserver : public WebContentsObserver {
  public:
-  explicit MediaWebContentsObserver(WebContents* web_contents);
+  explicit MediaWebContentsObserver(WebContentsImpl* web_contents);
   ~MediaWebContentsObserver() override;
 
-  // WebContentsObserver implementations.
-  void RenderFrameDeleted(RenderFrameHost* render_frame_host) override;
+  // Called when the audible state has changed.  If inaudible any audio power
+  // save blockers are released.
+  void MaybeUpdateAudibleState(bool recently_audible);
 
-#if defined(OS_ANDROID)
+  // WebContentsObserver implementation.
+  void RenderFrameDeleted(RenderFrameHost* render_frame_host) override;
   bool OnMessageReceived(const IPC::Message& message,
                          RenderFrameHost* render_frame_host) override;
+  void WasShown() override;
+  void WasHidden() override;
 
-  // Helper functions to handle media player IPC messages. Returns whether the
-  // |message| is handled in the function.
-  bool OnMediaPlayerMessageReceived(const IPC::Message& message,
-                                    RenderFrameHost* render_frame_host);
-  bool OnMediaPlayerSetCdmMessageReceived(const IPC::Message& message,
-                                          RenderFrameHost* render_frame_host);
-
+#if defined(OS_ANDROID)
   // Gets the media player manager associated with |render_frame_host|. Creates
   // a new one if it doesn't exist. The caller doesn't own the returned pointer.
   BrowserMediaPlayerManager* GetMediaPlayerManager(
       RenderFrameHost* render_frame_host);
 
-  void OnSetCdm(RenderFrameHost* render_frame_host, int player_id, int cdm_id);
-
 #if defined(VIDEO_HOLE)
   void OnFrameInfoUpdated();
 #endif  // defined(VIDEO_HOLE)
+#endif  // defined(OS_ANDROID)
+
+  bool has_audio_power_save_blocker_for_testing() const {
+    return audio_power_save_blocker_;
+  }
+
+  bool has_video_power_save_blocker_for_testing() const {
+    return video_power_save_blocker_;
+  }
 
  private:
+  bool OnMediaPlayerDelegateMessageReceived(const IPC::Message& message,
+                                            RenderFrameHost* render_frame_host);
+
+  void OnMediaPlayingNotification(int64_t player_cookie,
+                                  bool has_video,
+                                  bool has_audio,
+                                  bool is_remote);
+  void OnMediaPausedNotification(int64_t player_cookie);
+
+  // Clear |render_frame_host|'s tracking entry for its power save blockers.
+  void ClearPowerSaveBlockers(RenderFrameHost* render_frame_host);
+
+  // Creates an audio or video power save blocker respectively.
+  void CreateAudioPowerSaveBlocker();
+  void CreateVideoPowerSaveBlocker();
+
+  // Releases the audio power save blockers if |active_audio_players_| is empty.
+  // Likewise, releases the video power save blockers if |active_video_players_|
+  // is empty.
+  void MaybeReleasePowerSaveBlockers();
+
+  // Helper methods for adding or removing player entries in |player_map| under
+  // the key |render_frame_message_source_|.
+  using PlayerList = std::vector<int64_t>;
+  using ActiveMediaPlayerMap = std::map<RenderFrameHost*, PlayerList>;
+  void AddMediaPlayerEntry(int64_t player_cookie,
+                           ActiveMediaPlayerMap* player_map);
+  void RemoveMediaPlayerEntry(int64_t player_cookie,
+                              ActiveMediaPlayerMap* player_map);
+  // Removes all entries from |player_map| for |render_frame_host|.
+  void RemoveAllMediaPlayerEntries(RenderFrameHost* render_frame_host,
+                                   ActiveMediaPlayerMap* player_map);
+
+#if defined(OS_ANDROID)
+  // Helper functions to handle media player IPC messages. Returns whether the
+  // |message| is handled in the function.
+  bool OnMediaPlayerMessageReceived(const IPC::Message& message,
+                                    RenderFrameHost* render_frame_host);
+
+  bool OnMediaPlayerSetCdmMessageReceived(const IPC::Message& message,
+                                          RenderFrameHost* render_frame_host);
+
+  void OnSetCdm(RenderFrameHost* render_frame_host, int player_id, int cdm_id);
+
   // Map from RenderFrameHost* to BrowserMediaPlayerManager.
-  typedef base::ScopedPtrHashMap<uintptr_t,
-                                 scoped_ptr<BrowserMediaPlayerManager>>
-      MediaPlayerManagerMap;
+  using MediaPlayerManagerMap =
+      base::ScopedPtrHashMap<RenderFrameHost*,
+                             scoped_ptr<BrowserMediaPlayerManager>>;
   MediaPlayerManagerMap media_player_managers_;
 #endif  // defined(OS_ANDROID)
 
- private:
+  // Tracking variables and associated power save blockers for media playback.
+  ActiveMediaPlayerMap active_audio_players_;
+  ActiveMediaPlayerMap active_video_players_;
+  scoped_ptr<PowerSaveBlocker> audio_power_save_blocker_;
+  scoped_ptr<PowerSaveBlocker> video_power_save_blocker_;
+
+  WebContentsImpl* web_contents_;

[ncarter (slow), 2015/12/02 17:49:31]

WCO implementations typically don't need to cache a pointer to the WebContents;
they can use the web_contents() accessor in WebContentsObserver.

[DaleCurtis, 2015/12/02 19:55:46]

This is necessary because MediaStartedPlaying/MediaPaused are only on the WCI
and not the WC interface.

[qinmin, 2015/12/02 21:54:58]

we can do a cast to WCI when MediaStartedPlaying/MediaPaused is called, right?

[DaleCurtis, 2015/12/03 01:35:08]

I forget if that's allowed here or if there are fakes/mocks/other injectables
which might be present. 

[qinmin, 2015/12/03 15:46:31]

see example here:
https://code.google.com/p/chromium/codesearch#chromium/src/content/browser/de...

[DaleCurtis, 2015/12/04 01:36:27]

Thanks! Done.

[ncarter (slow), 2015/12/05 00:43:33]

To confirm: inside of the content/ implementation, it's always okay to cast from
an interface class to an Impl class, except for RenderProcessHostImpl.
WebContents to WebContentsImpl is especially okay.

https://www.chromium.org/developers/content-module/content-api mentions this
briefly.

+
+  // Used during IPC message dispatching from the RenderFrame so that the
+  // handlers can get a pointer to the RVH through which the message was
+  // received.
+  RenderFrameHost* render_frame_message_source_;
+
   DISALLOW_COPY_AND_ASSIGN(MediaWebContentsObserver);
 };