Fixed the audio backgrounding bug

content/public/test/mock_render_process_host.cc

 // 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.
 
 #include "content/public/test/mock_render_process_host.h"
 
 #include <algorithm>
 #include <utility>
 #include <vector>
 
@@ skipping 120 matching lines @@
 void MockRenderProcessHost::WidgetRestored() {
 }
 
 void MockRenderProcessHost::WidgetHidden() {
 }
 
 int MockRenderProcessHost::VisibleWidgetCount() const {
   return 1;
 }
 
+void MockRenderProcessHost::AudioStateChanged() {
+}
+
 bool MockRenderProcessHost::IsForGuestsOnly() const {
   return is_for_guests_only_;
 }
 
 StoragePartition* MockRenderProcessHost::GetStoragePartition() const {
   return BrowserContext::GetDefaultStoragePartition(browser_context_);
 }
 
 void MockRenderProcessHost::AddWord(const base::string16& word) {
 }
@@ skipping 194 matching lines @@
   for (ScopedVector<MockRenderProcessHost>::iterator it = processes_.begin();
        it != processes_.end(); ++it) {
     if (*it == host) {
       processes_.weak_erase(it);
       break;
     }
   }
 }
 
 }  // content