Migrate MediaStream test code from content/shell/renderer/ to content/test/.

content/public/renderer/content_renderer_client.cc

Index: content/public/renderer/content_renderer_client.cc
diff --git a/content/public/renderer/content_renderer_client.cc b/content/public/renderer/content_renderer_client.cc
index 13998ac995712bf83d30b3d3b6e5922d94ef67c3..42d81bf0e12a19584390e464e8bdac76aa73bb4a 100644
--- a/content/public/renderer/content_renderer_client.cc
+++ b/content/public/renderer/content_renderer_client.cc
@@ -54,11 +54,6 @@ ContentRendererClient::OverrideCreateWebRTCPeerConnectionHandler(
   return NULL;
 }
 
-webkit_media::MediaStreamClient*
-ContentRendererClient::OverrideCreateMediaStreamClient() {
-  return NULL;
-}
-
 WebKit::WebMIDIAccessor*
 ContentRendererClient::OverrideCreateMIDIAccessor(
     WebKit::WebMIDIAccessorClient* client) {