DirectCompositorFrameSink Uses CompositorFrameSinkSupport

cc/surfaces/surface_manager.cc

Index: cc/surfaces/surface_manager.cc
diff --git a/cc/surfaces/surface_manager.cc b/cc/surfaces/surface_manager.cc
index 34bd3948255f19625156ef54b0b5bdc6ae80e388..80ff06c09d122465b5f32547bb23bd333600e67e 100644
--- a/cc/surfaces/surface_manager.cc
+++ b/cc/surfaces/surface_manager.cc
@@ -88,8 +88,7 @@ void SurfaceManager::DidSatisfySequences(const FrameSinkId& frame_sink_id,
 }
 
 void SurfaceManager::RegisterFrameSinkId(const FrameSinkId& frame_sink_id) {
-  bool inserted = valid_frame_sink_ids_.insert(frame_sink_id).second;
-  DCHECK(inserted);
+  valid_frame_sink_ids_.insert(frame_sink_id);

[jbauman, 2017/01/07 01:17:26]

Why is removing this DCHECK necessary? We shouldn't be registering the same
frame sink twice.

[Alex Z., 2017/01/07 14:35:49]

Originally, DirectCompositorFrameSink::BindToClient() doesn't call 
RegisterFrameSinkId(). CompositorFrameSinkSupport calls RegisterFrameSinkId() 
in its constructor, which triggers the DCHECK for DirectCompositorFrameSink.

fsamuel told me to remove the DCHECK instead of exposing RegisterFrameSinkId()
to GpuCompositorFrameSink or make a custom CompositorFrameSink() for 
DirectCompositorFrameSink.

[Fady Samuel, 2017/01/08 16:36:32]

ui::Compositor Registers the FrameSinkId first:
https://cs.chromium.org/chromium/src/ui/compositor/compositor.cc?sq=package:c...

However, we eventually want to get rid of that in favor of the SurfaceReference
approach to reference tracking. We're not there yet. For the time being, we are
registering the FrameSinkId in CompositorFrameSinkSupport. However, while we're
using SurfaceSequences, we cannot get rid of RegisterFrameSinkId in
ui::Compositor, so I thought getting rid of the DCHECK would be easier for now.

Note that once SurfaceReferences are used everywhere, RegisterFrameSinkId and
InvalidateFrameSinkId will likely go away.

 }
 
 void SurfaceManager::InvalidateFrameSinkId(const FrameSinkId& frame_sink_id) {