cc: Make scheduling be driven by vsync for android webview.

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 f77df28b783d5ff3f8d411221cdef6823b66904f..04384423a14584f055bd90cfffa53781d1ee5013 100644
--- a/cc/scheduler/scheduler_state_machine.h
+++ b/cc/scheduler/scheduler_state_machine.h
@@ -64,7 +64,8 @@ class CC_EXPORT SchedulerStateMachine {
   static const char* BeginImplFrameStateToString(BeginImplFrameState state);
 
   enum BeginImplFrameDeadlineMode {
-    BEGIN_IMPL_FRAME_DEADLINE_MODE_IMMEDIATE,
+    BEGIN_IMPL_FRAME_DEADLINE_MODE_IMMEDIATE_SYNCHRONOUS,
+    BEGIN_IMPL_FRAME_DEADLINE_MODE_IMMEDIATE_ASYNCHRONOUS,
     BEGIN_IMPL_FRAME_DEADLINE_MODE_REGULAR,
     BEGIN_IMPL_FRAME_DEADLINE_MODE_LATE,
   };
@@ -111,6 +112,7 @@ class CC_EXPORT SchedulerStateMachine {
     ACTION_DRAW_AND_SWAP_ABORT,
     ACTION_BEGIN_OUTPUT_SURFACE_CREATION,
     ACTION_PREPARE_TILES,
+    ACTION_INVALIDATE_OUTPUT_SURFACE,
   };
   static const char* ActionToString(Action action);
 
@@ -129,12 +131,6 @@ class CC_EXPORT SchedulerStateMachine {
   // SetNeedsBeginFrames(BeginFrameNeeded()) on the frame source.
   bool ShouldSetNeedsBeginFrames(bool frame_source_needs_begin_frames) const;
 
-  // Indicates that we need to independently poll for new state and actions
-  // because we can't expect a BeginImplFrame. This is mostly used to avoid
-  // drawing repeat frames with the synchronous compositor without dropping
-  // necessary actions on the floor.
-  bool ShouldPollForAnticipatedDrawTriggers() const;
-
   // Indicates that the system has entered and left a BeginImplFrame callback.
   // The scheduler will not draw more than once in a given BeginImplFrame
   // callback nor send more than one BeginMainFrame message.
@@ -151,15 +147,6 @@ class CC_EXPORT SchedulerStateMachine {
   // impl thread to draw, it is in a high latency mode.
   bool MainThreadIsInHighLatencyMode() const;
 
-  // PollForAnticipatedDrawTriggers is used by the synchronous compositor to
-  // avoid requesting BeginImplFrames when we won't actually draw but still
-  // need to advance our state at vsync intervals.
-  void DidEnterPollForAnticipatedDrawTriggers();
-  void DidLeavePollForAnticipatedDrawTriggers();
-  bool inside_poll_for_anticipated_draw_triggers() const {
-    return inside_poll_for_anticipated_draw_triggers_;
-  }
-
   // Indicates whether the LayerTreeHostImpl is visible.
   void SetVisible(bool visible);
   bool visible() const { return visible_; }
@@ -246,8 +233,6 @@ class CC_EXPORT SchedulerStateMachine {
   // True if we need to abort draws to make forward progress.
   bool PendingDrawsShouldBeAborted() const;
 
-  bool SupportsProactiveBeginFrame() const;
-
   void SetContinuousPainting(bool continuous_painting) {
     continuous_painting_ = continuous_painting;
   }
@@ -288,12 +273,14 @@ class CC_EXPORT SchedulerStateMachine {
   bool ShouldSendBeginMainFrame() const;
   bool ShouldCommit() const;
   bool ShouldPrepareTiles() const;
+  bool ShouldInvalidateOutputSurface() const;
 
-  void AdvanceCurrentFrameNumber();
+  void AdvanceFrame();
   bool HasAnimatedThisFrame() const;
   bool HasSentBeginMainFrameThisFrame() const;
   bool HasRequestedSwapThisFrame() const;
   bool HasSwappedThisFrame() const;
+  bool HasInvalidatedOutputSurfaceThisFrame() const;
 
   void UpdateStateOnCommit(bool commit_had_no_updates);
   void UpdateStateOnActivation();
@@ -315,6 +302,7 @@ class CC_EXPORT SchedulerStateMachine {
   int last_frame_number_swap_performed_;
   int last_frame_number_swap_requested_;
   int last_frame_number_begin_main_frame_sent_;
+  int last_frame_number_invalidate_output_surface_performed_;
 
   // prepare_tiles_funnel_ is "filled" each time PrepareTiles is called
   // and "drained" on each BeginImplFrame. If the funnel gets too full,
@@ -328,7 +316,6 @@ class CC_EXPORT SchedulerStateMachine {
   bool needs_animate_;
   bool needs_prepare_tiles_;
   bool needs_commit_;
-  bool inside_poll_for_anticipated_draw_triggers_;
   bool visible_;
   bool can_start_;
   bool can_draw_;