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 b03b81e7ba8c8a050c68fe3bfd91ca10e51d8039..412e5c4c4dedfe7f2cd2064a3d47f43407a28e0e 100644
--- a/cc/surfaces/surface_manager.cc
+++ b/cc/surfaces/surface_manager.cc
@@ -120,8 +120,7 @@ void SurfaceManager::SatisfySequence(const SurfaceSequence& sequence) {
 }
 
 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);

[danakj, 2017/01/31 20:19:17]

Why this change?

[Alex Z., 2017/01/31 21:09:30]

From fsamuel's earlier comment:

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.

[danakj, 2017/01/31 21:49:40]

Can we have a parameter passed around maybe saying to use refs or surfaces. And
ui::Compositor would register if appropriate, and CompositorFrameSinkSupport
would if appropriate? Or would that be insane?
FWIW, likely shouldn't motivate code too much, as it's also likely to change.

[danakj, 2017/02/03 18:48:43]

I'm not seeing anything in the replies to this, did I miss it? And how would we
ensure this check came back in a timely manner if we remove it now?

[Alex Z., 2017/02/03 19:32:20]

I added a flag to CompositorFrameSinkSupport in patchset 15 where 
CompositorFrameSinkSupport wouldn't register or invalidate 
FrameSinkId if it's supporting DCFS. fsamuel wasn't happy about 
using the flag as he'd like to go with the design where CFSSupport 
manages FrameSinkId. 

Would adding a "TODO: DCHECK if the insert is successful." be enough assurance?

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