cc: Heuristic for Renderer latency recovery

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 <string>
 
 #include "base/basictypes.h"
@@ skipping 127 matching lines @@
   void OnBeginImplFrameIdle();
   BeginImplFrameState begin_impl_frame_state() const {
     return begin_impl_frame_state_;
   }
   BeginImplFrameDeadlineMode CurrentBeginImplFrameDeadlineMode() const;
 
   // If the main thread didn't manage to produce a new frame in time for the
   // impl thread to draw, it is in a high latency mode.
   bool MainThreadIsInHighLatencyMode() const;
 
+  bool ImplThreadIsLikelyInHighLatencyMode() const {

[sunnyps, 2015/05/22 21:15:05]

Rename this to IsSwapThrottled or similar. We are only likely in high latency
mode if this is true at the start of the frame.

[brianderson, 2015/06/30 22:03:52]

Done.

+    return pending_swaps_ >= max_pending_swaps_;
+  }
+
   // Indicates whether the LayerTreeHostImpl is visible.
   void SetVisible(bool visible);
   bool visible() const { return visible_; }
 
   // Indicates that a redraw is required, either due to the impl tree changing
   // or the screen being damaged and simply needing redisplay.
   void SetNeedsRedraw();
   bool needs_redraw() const { return needs_redraw_; }
 
   void SetNeedsAnimate();
@@ skipping 28 matching lines @@
     return impl_latency_takes_priority_;
   }
 
   // Indicates whether ACTION_DRAW_AND_SWAP_IF_POSSIBLE drew to the screen.
   void DidDrawIfPossibleCompleted(DrawResult result);
 
   // Indicates that a new commit flow needs to be performed, either to pull
   // updates from the main thread to the impl, or to push deltas from the impl
   // thread to main.
   void SetNeedsCommit();
+  bool needs_commit() const { return needs_commit_; }
 
   // Call this only in response to receiving an ACTION_SEND_BEGIN_MAIN_FRAME
   // from NextAction.
   // Indicates that all painting is complete.
   void NotifyReadyToCommit();
 
   // Call this only in response to receiving an ACTION_SEND_BEGIN_MAIN_FRAME
   // from NextAction if the client rejects the BeginMainFrame message.
   void BeginMainFrameAborted(CommitEarlyOutReason reason);
 
   // Set that we can create the first OutputSurface and start the scheduler.
   void SetCanStart() { can_start_ = true; }
   // Allow access of the can_start_ state in tests.
   bool CanStartForTesting() const { return can_start_; }
 
+  // Indicates production should be skipped to recover latency.
   void SetSkipNextBeginMainFrameToReduceLatency();
 
   // Indicates whether drawing would, at this time, make sense.
   // CanDraw can be used to suppress flashes or checkerboarding
   // when such behavior would be undesirable.
   void SetCanDraw(bool can);
 
   // Indicates that scheduled BeginMainFrame is started.
   void NotifyBeginMainFrameStarted();
 
@@ skipping 105 matching lines @@
   bool needs_commit_;
   bool visible_;
   bool can_start_;
   bool can_draw_;
   bool has_pending_tree_;
   bool pending_tree_is_ready_for_activation_;
   bool active_tree_needs_first_draw_;
   bool did_create_and_initialize_first_output_surface_;
   bool impl_latency_takes_priority_;
   bool skip_next_begin_main_frame_to_reduce_latency_;
-  bool skip_begin_main_frame_to_reduce_latency_;
   bool continuous_painting_;
   bool children_need_begin_frames_;
   bool defer_commits_;
   bool video_needs_begin_frames_;
   bool last_commit_had_no_updates_;
   bool wait_for_active_tree_ready_to_draw_;
   bool did_request_swap_in_last_frame_;
   bool did_perform_swap_in_last_draw_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SchedulerStateMachine);
 };
 
 }  // namespace cc
 
 #endif  // CC_SCHEDULER_SCHEDULER_STATE_MACHINE_H_