cc: Allow sending BeginMainFrame before draw or activation

cc/scheduler/scheduler.cc

 // Copyright 2011 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 "cc/scheduler/scheduler.h"
 
 #include <algorithm>
 #include "base/auto_reset.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
@@ skipping 354 matching lines @@
       case SchedulerStateMachine::ACTION_ACQUIRE_LAYER_TEXTURES_FOR_MAIN_THREAD:
         client_->ScheduledActionAcquireLayerTexturesForMainThread();
         break;
       case SchedulerStateMachine::ACTION_MANAGE_TILES:
         client_->ScheduledActionManageTiles();
         break;
     }
   } while (action != SchedulerStateMachine::ACTION_NONE);
 
   SetupNextBeginImplFrameIfNeeded();
-  client_->DidAnticipatedDrawTimeChange(AnticipatedDrawTime());
+
+  if (SchedulerStateMachine::COMMIT_STATE_FRAME_IN_PROGRESS ==

[enne (OOO), 2014/01/23 21:51:55]

Why do you only update the anticipated draw time during commit?

[brianderson, 2014/01/23 23:31:35]

It avoided a PostTask storm of some sort. I'll see if there is a better
solution.

+      state_machine_.commit_state())
+    client_->DidAnticipatedDrawTimeChange(AnticipatedDrawTime());
 
   if (state_machine_.ShouldTriggerBeginImplFrameDeadlineEarly())
     PostBeginImplFrameDeadline(base::TimeTicks());
 }
 
 bool Scheduler::WillDrawIfNeeded() const {
   return !state_machine_.PendingDrawsShouldBeAborted();
 }
 
 bool Scheduler::CanCommitAndActivateBeforeDeadline() const {
   // Check if the main thread computation and commit can be finished before the
   // impl thread's deadline.
   base::TimeTicks estimated_draw_time =
       last_begin_impl_frame_args_.frame_time +
       client_->BeginMainFrameToCommitDurationEstimate() +
       client_->CommitToActivateDurationEstimate();
 
   return estimated_draw_time < last_begin_impl_frame_args_.deadline;
 }
 
 }  // namespace cc