Create a new action triggered when a BeginMainFrame is not expected before vsync

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 cd4a7f2ee6689c969354e511fad775a8980d3355..79cf904677f726969cf59d3febdf2e2b0f43382e 100644
--- a/cc/scheduler/scheduler_state_machine.h
+++ b/cc/scheduler/scheduler_state_machine.h
@@ -123,6 +123,7 @@ class CC_EXPORT SchedulerStateMachine {
     ACTION_BEGIN_COMPOSITOR_FRAME_SINK_CREATION,
     ACTION_PREPARE_TILES,
     ACTION_INVALIDATE_COMPOSITOR_FRAME_SINK,
+    ACTION_DO_IDLE_WORK,
   };
   static const char* ActionToString(Action action);
 
@@ -131,6 +132,7 @@ class CC_EXPORT SchedulerStateMachine {
 
   Action NextAction() const;
   void WillSendBeginMainFrame();
+  void WillDoIdleWork();
   void WillCommit(bool commit_had_no_updates);
   void WillActivate();
   void WillDraw();
@@ -274,6 +276,7 @@ class CC_EXPORT SchedulerStateMachine {
   bool PendingDrawsShouldBeAborted() const;
 
   bool CouldSendBeginMainFrame() const;
+  bool CouldDoIdleWork() const;
 
   void SetDeferCommits(bool defer_commits);
 
@@ -318,6 +321,7 @@ class CC_EXPORT SchedulerStateMachine {
   bool ShouldCommit() const;
   bool ShouldPrepareTiles() const;
   bool ShouldInvalidateCompositorFrameSink() const;
+  bool ShouldDoIdleWork() const;
 
   void WillDrawInternal();
   void WillPerformImplSideInvalidationInternal();
@@ -359,6 +363,7 @@ class CC_EXPORT SchedulerStateMachine {
   bool send_begin_main_frame_funnel_;
   bool invalidate_compositor_frame_sink_funnel_;
   bool impl_side_invalidation_funnel_;
+  bool do_idle_work_funnel_;
   // prepare_tiles_funnel_ is "filled" each time PrepareTiles is called
   // and "drained" on each BeginImplFrame. If the funnel gets too full,
   // we start throttling ACTION_PREPARE_TILES such that we average one