Remove CompositorObserver::OnCompositingEnded()

ui/compositor/compositor.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/compositor/compositor.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <deque>
@@ skipping 511 matching lines @@
   // the Compositor.
   NOTREACHED();
 }
 
 void Compositor::DidCommit() {
   DCHECK(!IsLocked());
   for (auto& observer : observer_list_)
     observer.OnCompositingDidCommit(this);
 }
 
-void Compositor::DidReceiveCompositorFrameAck() {
-  ++committed_frame_number_;
-  for (auto& observer : observer_list_)
-    observer.OnCompositingEnded(this);
-}
+void Compositor::DidReceiveCompositorFrameAck() {}
 
 void Compositor::DidSubmitCompositorFrame() {
   base::TimeTicks start_time = base::TimeTicks::Now();
+  ++committed_frame_number_;

[danakj, 2017/03/28 16:04:54]

This would change the result of Layer::GetFrameNumber. I started trying to track
down all callers of that to see if any would happen after
DidSubmitCompositorFrame and before DidReceiveCompositorFrameAck, but there's
many callers, so can you do that to convince yourself and me that it's okay? In
the end its about animation ticking afaict. If you're stuck ajuma can help.

[Fady Samuel, 2017/03/28 17:35:05]

As I said offline, we can undo this change and land the rest of the patch then
figure out the right way to measure animation jank separately.

[Alex Z., 2017/03/28 18:08:27]

This change has been reverted in the latest patch.

   for (auto& observer : observer_list_)
     observer.OnCompositingStarted(this, start_time);
 }
 
 void Compositor::SetOutputIsSecure(bool output_is_secure) {
   if (context_factory_private_)
     context_factory_private_->SetOutputIsSecure(this, output_is_secure);
 }
 
 const cc::LayerTreeDebugState& Compositor::GetLayerTreeDebugState() const {
@@ skipping 26 matching lines @@
   for (auto& observer : observer_list_)
     observer.OnCompositingLockStateChanged(this);
 }
 
 void Compositor::CancelCompositorLock() {
   if (compositor_lock_)
     compositor_lock_->CancelLock();
 }
 
 }  // namespace ui