Support exposing Mojo services between render frames, render threads, and their respective hosts.

content/public/test/mock_render_process_host.cc

Index: content/public/test/mock_render_process_host.cc
diff --git a/content/public/test/mock_render_process_host.cc b/content/public/test/mock_render_process_host.cc
index 7fb8d0311a923425f82ef668912b6404cf4d0130..d503ca5a5914bf1bcb6580ef766e08f5113bf6df 100644
--- a/content/public/test/mock_render_process_host.cc
+++ b/content/public/test/mock_render_process_host.cc
@@ -223,6 +223,10 @@ void MockRenderProcessHost::ResumeRequestsForView(int route_id) {
 void MockRenderProcessHost::NotifyTimezoneChange() {
 }
 
+ServiceRegistry* MockRenderProcessHost::GetServiceRegistry() {
+  return NULL;
+}
+
 void MockRenderProcessHost::FilterURL(bool empty_allowed, GURL* url) {
   RenderProcessHostImpl::FilterURL(this, empty_allowed, url);
 }