Fixed the audio backgrounding bug

content/public/test/mock_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_TEST_MOCK_RENDER_PROCESS_HOST_H_
 #define CONTENT_PUBLIC_TEST_MOCK_RENDER_PROCESS_HOST_H_
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_vector.h"
 #include "base/observer_list.h"
@@ skipping 29 matching lines @@
   bool Init() override;
   int GetNextRoutingID() override;
   void AddRoute(int32 routing_id, IPC::Listener* listener) override;
   void RemoveRoute(int32 routing_id) override;
   void AddObserver(RenderProcessHostObserver* observer) override;
   void RemoveObserver(RenderProcessHostObserver* observer) override;
   void ShutdownForBadMessage() override;
   void WidgetRestored() override;
   void WidgetHidden() override;
   int VisibleWidgetCount() const override;
+  void AudioStateChanged() override;
   bool IsForGuestsOnly() const override;
   StoragePartition* GetStoragePartition() const override;
   virtual void AddWord(const base::string16& word);
   bool Shutdown(int exit_code, bool wait) override;
   bool FastShutdownIfPossible() override;
   bool FastShutdownStarted() const override;
   base::ProcessHandle GetHandle() const override;
   int GetID() const override;
   bool HasConnection() const override;
   void SetIgnoreInputEvents(bool ignore_input_events) override;
@@ skipping 99 matching lines @@
   // for deleting all MockRenderProcessHosts that have not deleted by a test in
   // the destructor and prevent them from being leaked.
   mutable ScopedVector<MockRenderProcessHost> processes_;
 
   DISALLOW_COPY_AND_ASSIGN(MockRenderProcessHostFactory);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_TEST_MOCK_RENDER_PROCESS_HOST_H_