Implements AudioMessageFilter as member in RenderThread

content/renderer/media/audio_message_filter.h

Index: content/renderer/media/audio_message_filter.h
===================================================================
--- content/renderer/media/audio_message_filter.h	(revision 88939)
+++ content/renderer/media/audio_message_filter.h	(working copy)
@@ -52,9 +52,12 @@
     virtual ~Delegate() {}
   };
 
-  explicit AudioMessageFilter(int32 route_id);
+  explicit AudioMessageFilter();
   virtual ~AudioMessageFilter();
 
+  // Sets the routing ID for all transmitted messages.
+  void SetRoutingID(int32 id);
+
   // Add a delegate to the map and return id of the entry.
   int32 AddDelegate(Delegate* delegate);
 
@@ -66,6 +69,8 @@
 
   MessageLoop* message_loop() { return message_loop_; }
 
+  int32 routing_id() { return routing_id_; }
+
  private:
   // For access to |message_loop_|.
   friend class AudioRendererImplTest;
@@ -110,7 +115,7 @@
 
   IPC::Channel* channel_;
 
-  int32 route_id_;
+  int32 routing_id_;
 
   MessageLoop* message_loop_;