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 108 matching lines @@
   scoped_refptr<base::trace_event::ConvertableToTraceFormat> AsValue() const;
   void AsValueInto(base::trace_event::TracedValue* dict) const;
 
   Action NextAction() const;
   void UpdateState(Action action);
 
   // Indicates whether the impl thread needs a BeginImplFrame callback in order
   // to make progress.
   bool BeginFrameNeeded() const;
 
+  // Notifies the state machine that the Scheduler skipped a BeginImplFrame
+  // so the state machine can reset associated state.
+  void DidSkipBeginImplFrameToReduceLatency();
+
   // 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.
   void OnBeginImplFrame();
   void OnBeginImplFrameDeadlinePending();
   // Indicates that the scheduler has entered the draw phase. The scheduler
   // will not draw more than once in a single draw phase.
   // TODO(sunnyps): Rename OnBeginImplFrameDeadline to OnDraw or similar.
   void OnBeginImplFrameDeadline();
   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 swaps_are_likely_high_latency() const {
+    return swaps_are_likely_high_latency_;
+  }
+
   // 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 NeedsCommitForTesting() const { return needs_commit_; }

[sunnyps, 2015/05/12 00:36:25]

nit: This could be renamed to needs_commit. That way it follows the naming
convention for inline methods. Given that this is a const accessor I see no harm
in exposing this.

[brianderson, 2015/05/12 19:25:17]

Done.

 
   // 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);
 
@@ skipping 104 matching lines @@
   bool invalidate_output_surface_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
   // PrepareTiles per BeginImplFrame.
   int prepare_tiles_funnel_;
 
   int consecutive_checkerboard_animations_;
   int max_pending_swaps_;
   int pending_swaps_;
+  bool swaps_are_likely_high_latency_;
+  bool swap_throttled_in_last_deadline_;
   bool needs_redraw_;
   bool needs_animate_;
   bool needs_prepare_tiles_;
   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_;
@@ skipping 10 matching lines @@
   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_