Mustash: Ensure surfaces submitted to Mus by WM and embedders contain Surfaces with embeded content.

services/ui/ws/server_window_compositor_frame_sink_manager.cc

Index: services/ui/ws/server_window_compositor_frame_sink_manager.cc
diff --git a/services/ui/ws/server_window_compositor_frame_sink_manager.cc b/services/ui/ws/server_window_compositor_frame_sink_manager.cc
index 51091085e78f7173968a0d00ce72a8d85a6461ec..af0c6b0ffac0270bdb8682e52a94da1e5741ea98 100644
--- a/services/ui/ws/server_window_compositor_frame_sink_manager.cc
+++ b/services/ui/ws/server_window_compositor_frame_sink_manager.cc
@@ -29,9 +29,7 @@ bool ServerWindowCompositorFrameSinkManager::ShouldDraw() {
     return true;
 
   waiting_for_initial_frames_ = !IsCompositorFrameSinkReadyAndNonEmpty(

[sky, 2016/12/16 21:50:29]

Can we replace waiting_for_initial_frames_ with
IsCompositorFrameSinkReadyAndNonEmpty(DEFAULT)?

[mfomitchev, 2016/12/23 00:03:49]

Actually, it seems like currently this is always false (with or without my CL),
because it is initialized to false unless ui::mojom::kWaitForUnderlay_Property
is set, and that is never set. I've added a TODO to  clean this up. We could in
theory delete a bunch of code here. Will confirm with fsamuel and do it in a
separate CL if that's okay.

-                                    mojom::CompositorFrameSinkType::DEFAULT) ||
-                                !IsCompositorFrameSinkReadyAndNonEmpty(
-                                    mojom::CompositorFrameSinkType::UNDERLAY);
+      mojom::CompositorFrameSinkType::DEFAULT);
   return !waiting_for_initial_frames_;
 }