Adds BeginFrameControl via DevTools.

cc/scheduler/scheduler_state_machine.h

 // 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.
 
 #ifndef CC_SCHEDULER_SCHEDULER_STATE_MACHINE_H_
 #define CC_SCHEDULER_SCHEDULER_STATE_MACHINE_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 252 matching lines @@
   // True if we need to abort draws to make forward progress.
   bool PendingDrawsShouldBeAborted() const;
 
   bool CouldSendBeginMainFrame() const;
 
   void SetDeferCommits(bool defer_commits);
 
   void SetVideoNeedsBeginFrames(bool video_needs_begin_frames);
   bool video_needs_begin_frames() const { return video_needs_begin_frames_; }
 
+  void SetBeginFrameAllowsLatencyOptimizations(
+      bool allow_latency_optimizations);
+
  protected:
   bool BeginFrameRequiredForAction() const;
   bool BeginFrameNeededForVideo() const;
   bool ProactiveBeginFrameWanted() const;
 
   bool ShouldTriggerBeginImplFrameDeadlineImmediately() const;
 
   // True if we need to force activations to make forward progress.
   // TODO(sunnyps): Rename this to ShouldAbortCurrentFrame or similar.
   bool PendingActivationsShouldBeForced() const;
 
   bool ShouldBeginCompositorFrameSinkCreation() const;
   bool ShouldDraw() const;
+  bool ShouldForceDraw() const;
   bool ShouldActivatePendingTree() const;
   bool ShouldSendBeginMainFrame() const;
   bool ShouldCommit() const;
   bool ShouldPrepareTiles() const;
   bool ShouldInvalidateCompositorFrameSink() const;
 
   void WillDrawInternal();
   void DidDrawInternal(DrawResult draw_result);
 
   const SchedulerSettings settings_;
@@ skipping 41 matching lines @@
   ScrollHandlerState scroll_handler_state_;
   bool critical_begin_main_frame_to_activate_is_fast_;
   bool main_thread_missed_last_deadline_;
   bool skip_next_begin_main_frame_to_reduce_latency_;
   bool defer_commits_;
   bool video_needs_begin_frames_;
   bool last_commit_had_no_updates_;
   bool wait_for_ready_to_draw_;
   bool did_draw_in_last_frame_;
   bool did_submit_in_last_frame_;
+  bool begin_frame_allows_latency_optimizations_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SchedulerStateMachine);
 };
 
 }  // namespace cc
 
 #endif  // CC_SCHEDULER_SCHEDULER_STATE_MACHINE_H_