Create AudioRendererHost in BrowserRenderProcessHost and hook with ResourceMessageFilter

chrome/browser/renderer_host/browser_render_process_host.h

Index: chrome/browser/renderer_host/browser_render_process_host.h
diff --git a/chrome/browser/renderer_host/browser_render_process_host.h b/chrome/browser/renderer_host/browser_render_process_host.h
index 3e40d50751220642828c732ce86b8959e8ebda2c..d0895166599ddf7e7e1dac5bbbb58f76573d7a89 100644
--- a/chrome/browser/renderer_host/browser_render_process_host.h
+++ b/chrome/browser/renderer_host/browser_render_process_host.h
@@ -13,6 +13,7 @@
 #include "base/ref_counted.h"
 #include "base/scoped_ptr.h"
 #include "base/shared_memory.h"
+#include "chrome/browser/renderer_host/audio_renderer_host.h"
 #include "chrome/browser/renderer_host/render_process_host.h"
 #include "chrome/common/notification_observer.h"
 #include "webkit/glue/cache_manager.h"
@@ -136,6 +137,9 @@ class BrowserRenderProcessHost : public RenderProcessHost,
   // IO thread.
   scoped_refptr<RenderWidgetHelper> widget_helper_;
 
+  // The host of audio renderers in the renderer process.
+  scoped_refptr<AudioRendererHost> audio_renderer_host_;
+
   DISALLOW_COPY_AND_ASSIGN(BrowserRenderProcessHost);
 };