Implement aura::WindowPortMus::CreateCompositorFrameSink()

ui/aura/mus/window_tree_client.cc

Index: ui/aura/mus/window_tree_client.cc
diff --git a/ui/aura/mus/window_tree_client.cc b/ui/aura/mus/window_tree_client.cc
index 6bb5e41fc0dc6f3f97a04fe27b4ef6f500e91f6e..b840cd9ebeca0cc605d6e9c27b9530e7dcec8579 100644
--- a/ui/aura/mus/window_tree_client.cc
+++ b/ui/aura/mus/window_tree_client.cc
@@ -1382,13 +1382,7 @@ void WindowTreeClient::OnWindowSurfaceChanged(
   WindowMus* window = GetWindowByServerId(window_id);
   if (!window)
     return;
-
-  // If the parent is informed of a child's surface then that surface ID is
-  // guaranteed to be available in the display compositor so we set it as the
-  // fallback. If surface synchronization is enabled, the primary SurfaceInfo
-  // is created by the embedder, and the LocalSurfaceId is allocated by the
-  // embedder.
-  window->SetFallbackSurfaceInfo(surface_info);
+  window->SetSurfaceInfoFromServer(surface_info);

[Fady Samuel, 2017/05/30 18:36:42]

Please restore this.

[Peng, 2017/05/31 20:12:25]

As we discussed this offline. The SetPrimarySurfaceInfo is not used anymore. So
it is better to have this change.

 }
 
 void WindowTreeClient::OnDragDropStart(