Enable media stream layout test with content_shell.

content/public/renderer/content_renderer_client.h

Index: content/public/renderer/content_renderer_client.h
===================================================================
--- content/public/renderer/content_renderer_client.h	(revision 191534)
+++ content/public/renderer/content_renderer_client.h	(working copy)
@@ -39,6 +39,7 @@
 class WebRTCPeerConnectionHandlerClient;
 class WebThemeEngine;
 class WebURLRequest;
+class WebUserMediaClient;
 struct WebPluginParams;
 struct WebURLError;
 }
@@ -51,6 +52,7 @@
 }
 
 namespace webkit_media {
+class MediaStreamClient;
 class WebMediaPlayerDelegate;
 class WebMediaPlayerImpl;
 class WebMediaPlayerParams;
@@ -134,6 +136,14 @@
   virtual WebKit::WebMediaStreamCenter* OverrideCreateWebMediaStreamCenter(
       WebKit::WebMediaStreamCenterClient* client);
 
+  // Allows the embedder to provide a userMediaClient. If it
+  // returns NULL the content layer will create the userMediaClient.

[jam, 2013/04/01 15:51:45]

userMediaClient -> WebUserMediaClient

+  virtual WebKit::WebUserMediaClient* OverrideUserMediaClient();
+
+  // Allows the embedder to provide a MediaStreamClient. If it
+  // returns NULL the content layer will create the MediaStreamClient.
+  virtual webkit_media::MediaStreamClient* OverrideMediaStreamClient();
+
   // Allows the embedder to override creating a WebRTCPeerConnectionHandler. If
   // it returns NULL the content layer will create the connection handler.
   virtual WebKit::WebRTCPeerConnectionHandler*