OutputSurfaceMojo should bind its SurfacePtr on the impl thread

mojo/cc/output_surface_mojo.cc

Index: mojo/cc/output_surface_mojo.cc
diff --git a/mojo/cc/output_surface_mojo.cc b/mojo/cc/output_surface_mojo.cc
index 37a4eb0aada833cb0c22775dc1464ce1aa54626a..fbd2c9e5b6f4641ff13a7f7d46b462c8cd67cd5c 100644
--- a/mojo/cc/output_surface_mojo.cc
+++ b/mojo/cc/output_surface_mojo.cc
@@ -20,7 +20,6 @@ OutputSurfaceMojo::OutputSurfaceMojo(
       output_surface_mojo_client_(client),
       surface_(surface.Pass()),
       id_allocator_(id_namespace) {
-  surface_.set_client(this);
   capabilities_.delegated_rendering = true;
   capabilities_.max_frames_pending = 1;
 }
@@ -31,6 +30,11 @@ OutputSurfaceMojo::~OutputSurfaceMojo() {
 void OutputSurfaceMojo::ReturnResources(Array<ReturnedResourcePtr> resources) {
 }
 
+bool OutputSurfaceMojo::BindToClient(cc::OutputSurfaceClient* client) {
+  surface_.set_client(this);
+  return cc::OutputSurface::BindToClient(client);
+}
+
 void OutputSurfaceMojo::SwapBuffers(cc::CompositorFrame* frame) {
   gfx::Size frame_size =
       frame->delegated_frame_data->render_pass_list.back()->output_rect.size();