Pass Surface ID namespace to renderer compositors.

content/browser/renderer_host/render_widget_host_view_mac.mm

Index: content/browser/renderer_host/render_widget_host_view_mac.mm
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.mm b/content/browser/renderer_host/render_widget_host_view_mac.mm
index 22707f03bb721077c3e1e9261eaefbff4b6743a0..b6ef036904b4e6b4bc5267b823cbcc0020fa9f16 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/content/browser/renderer_host/render_widget_host_view_mac.mm
@@ -1563,6 +1563,13 @@ void RenderWidgetHostViewMac::WheelEventAck(
     [cocoa_view_ processedWheelEvent:event consumed:consumed];
 }
 
+uint32_t RenderWidgetHostViewMac::GetSurfaceIdNamespace() {
+  if (delegated_frame_host_)

[dcheng, 2015/05/14 14:53:38]

Can we add a comment that explains why this can happen on Mac but not Aura?

+    return delegated_frame_host_->GetSurfaceIdNamespace();
+
+  return 0;
+}
+
 bool RenderWidgetHostViewMac::Send(IPC::Message* message) {
   if (render_widget_host_)
     return render_widget_host_->Send(message);