Use AudioStreamMonitor to control power save blocking.

content/browser/web_contents/web_contents_impl.h

Index: content/browser/web_contents/web_contents_impl.h
diff --git a/content/browser/web_contents/web_contents_impl.h b/content/browser/web_contents/web_contents_impl.h
index 922829cfb74239d69953ad80bc5301ab5154648e..2e3bc9655051a83335292c6310c1525dcc5f4137 100644
--- a/content/browser/web_contents/web_contents_impl.h
+++ b/content/browser/web_contents/web_contents_impl.h
@@ -329,6 +329,7 @@ class CONTENT_EXPORT WebContentsImpl
                     const blink::WebFindOptions& options) OVERRIDE;
   virtual void StopFinding(StopFindAction action) OVERRIDE;
   virtual void InsertCSS(const std::string& css) OVERRIDE;
+  virtual bool WasRecentlyAudible() OVERRIDE;
 #if defined(OS_ANDROID)
   virtual base::android::ScopedJavaLocalRef<jobject> GetJavaWebContents()
       OVERRIDE;
@@ -902,12 +903,17 @@ class CONTENT_EXPORT WebContentsImpl
   // Removes browser plugin embedder if there is one.
   void RemoveBrowserPluginEmbedder();
 
-  // Clear |render_frame_host|'s PowerSaveBlockers.
+  // Clear |render_frame_host|'s tracking entry for |power_save_blocker_|.
   void ClearPowerSaveBlockers(RenderFrameHost* render_frame_host);
 
-  // Clear all PowerSaveBlockers, leave |power_save_blocker_| empty.
+  // Clear tracking entries for all RenderFrameHosts, clears
+  // |power_save_blocker_|.
   void ClearAllPowerSaveBlockers();
 
+  // Creates |power_save_blocker_|; must only be called if |power_save_blocker_|
+  // is NULL and |active_media_players_| is non-empty.
+  void CreatePowerSaveBlocker();
+
   // Helper function to invoke WebContentsDelegate::GetSizeForNewRenderView().
   gfx::Size GetSizeForNewRenderView();
 
@@ -973,16 +979,9 @@ class CONTENT_EXPORT WebContentsImpl
   // Helper classes ------------------------------------------------------------
 
 #if !defined(OS_CHROMEOS)
-  // Maps the RenderFrameHost to its media_player_cookie and PowerSaveBlocker
-  // pairs. Key is the RenderFrameHost, value is the map which maps
-  // player_cookie on to PowerSaveBlocker.
-  //
-  // ChromeOS does its own detection of audio and video.
-  typedef base::ScopedPtrHashMap<int64, PowerSaveBlocker>
-      PowerSaveBlockerMapEntry;
-  typedef base::ScopedPtrHashMap<uintptr_t, PowerSaveBlockerMapEntry>
-      PowerSaveBlockerMap;
-  PowerSaveBlockerMap power_save_blockers_;
+  typedef std::map<uintptr_t, int> ActiveMediaPlayerMap;
+  ActiveMediaPlayerMap active_media_players_;
+  scoped_ptr<content::PowerSaveBlocker> power_save_blocker_;
 #endif
 
   // Manages the frame tree of the page and process swaps in each node.