cc: Control defer_commits logic by Scheduler

cc/scheduler/scheduler_state_machine.h

Index: cc/scheduler/scheduler_state_machine.h
diff --git a/cc/scheduler/scheduler_state_machine.h b/cc/scheduler/scheduler_state_machine.h
index c69c9595837297b61ad33719e4e763d26875931e..6dbcbed31a288f56f6bc14c8f9d02a396af6f00f 100644
--- a/cc/scheduler/scheduler_state_machine.h
+++ b/cc/scheduler/scheduler_state_machine.h
@@ -243,6 +243,8 @@ class CC_EXPORT SchedulerStateMachine {
         impl_latency_takes_priority_on_battery;
   }
 
+  void SetDeferCommits(bool defer_commits);
+
   // TODO(zmo): This is temporary for debugging crbug.com/393331.
   // We should remove it afterwards.
   std::string GetStatesForDebugging() const;
@@ -323,6 +325,7 @@ class CC_EXPORT SchedulerStateMachine {
   bool continuous_painting_;
   bool impl_latency_takes_priority_on_battery_;
   bool children_need_begin_frames_;
+  bool defer_commits_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SchedulerStateMachine);