Fixed the audio backgrounding bug

content/public/browser/render_process_host.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_RENDER_PROCESS_HOST_H_
 #define CONTENT_PUBLIC_BROWSER_RENDER_PROCESS_HOST_H_
 
 #include <list>
 
 #include "base/basictypes.h"
@@ skipping 82 matching lines @@
   // bad_message::BadMessageReceived() or an equivalent method outside of the
   // content module.
   virtual void ShutdownForBadMessage() = 0;
 
   // Track the count of visible widgets. Called by listeners to register and
   // unregister visibility.
   virtual void WidgetRestored() = 0;
   virtual void WidgetHidden() = 0;
   virtual int VisibleWidgetCount() const = 0;
 
+  // Called when no audio streams remain for this render process host. Must be
+  // called on the UI thread.

[ncarter (slow), 2015/07/06 21:53:57]

All the methods of this class must be called on the UI thread, so you don't need
these comments.

[sebsg, 2015/08/02 16:44:23]

Done.

+  virtual void AudioStopped() = 0;
+
+  // Called when a first audio stream has started for this render process host.
+  // Must be called on the UI thread.
+  virtual void AudioStarted() = 0;
+
   // Indicates whether the current RenderProcessHost is exclusively hosting
   // guest RenderFrames. Not all guest RenderFrames are created equal.  A guest,
   // as indicated by BrowserPluginGuest::IsGuest, may coexist with other
   // non-guest RenderFrames in the same process if IsForGuestsOnly() is false.
   virtual bool IsForGuestsOnly() const = 0;
 
   // Returns the storage partition associated with this process.
   //
   // TODO(nasko): Remove this function from the public API once
   // URLRequestContextGetter's creation is moved into StoragePartition.
@@ skipping 221 matching lines @@
   static void SetMaxRendererProcessCount(size_t count);
 
   // Returns the current maximum number of renderer process hosts kept by the
   // content module.
   static size_t GetMaxRendererProcessCount();
 };
 
 }  // namespace content.
 
 #endif  // CONTENT_PUBLIC_BROWSER_RENDER_PROCESS_HOST_H_