Revert of cc: Remove frame queuing from the 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 16ee4d6b4347993e8af86e944202422f71389e46..6fd86a66e2ff4b0bb86995ee63a708bea1bc470d 100644
--- a/cc/scheduler/scheduler_state_machine.h
+++ b/cc/scheduler/scheduler_state_machine.h
@@ -82,6 +82,8 @@
     BEGIN_MAIN_FRAME_STATE_SENT,
     BEGIN_MAIN_FRAME_STATE_STARTED,
     BEGIN_MAIN_FRAME_STATE_READY_TO_COMMIT,
+    BEGIN_MAIN_FRAME_STATE_WAITING_FOR_ACTIVATION,
+    BEGIN_MAIN_FRAME_STATE_WAITING_FOR_DRAW,
   };
   static const char* BeginMainFrameStateToString(BeginMainFrameState state);
 
@@ -154,9 +156,6 @@
   // TODO(sunnyps): Rename OnBeginImplFrameDeadline to OnDraw or similar.
   void OnBeginImplFrameDeadline();
   void OnBeginImplFrameIdle();
-
-  int current_frame_number() const { return current_frame_number_; }
-
   BeginImplFrameState begin_impl_frame_state() const {
     return begin_impl_frame_state_;
   }