cc: Don't attempt main thread synchronization if it is slow.

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"
 #include "base/memory/scoped_ptr.h"
 #include "cc/base/cc_export.h"
 #include "cc/output/begin_frame_args.h"
 #include "cc/scheduler/commit_earlyout_reason.h"
 #include "cc/scheduler/draw_result.h"
 #include "cc/scheduler/scheduler_settings.h"
+#include "cc/tiles/tile_priority.h"
 
 namespace base {
 namespace trace_event {
 class ConvertableToTraceFormat;
 class TracedValue;
 }
 class Value;
 }
 
 namespace cc {
 
+enum ScrollHandlerState {

[Sami, 2015/11/18 19:46:05]

nit: could this be an enum class?

+  SCROLL_AFFECTS_SCROLL_HANDLER,
+  SCROLL_DOES_NOT_AFFECT_SCROLL_HANDLER,
+};
+const char* ScrollHandlerStateToString(ScrollHandlerState state);
+
 // The SchedulerStateMachine decides how to coordinate main thread activites
 // like painting/running javascript with rendering and input activities on the
 // impl thread.
 //
 // The state machine tracks internal state but is also influenced by external
 // state.  Internal state includes things like whether a frame has been
 // requested, while external state includes things like the current time being
 // near to the vblank time.
 //
 // The scheduler seperates "what to do next" from the updating of its internal
@@ skipping 148 matching lines @@
   // with a low resolution or checkerboarded tile.
   void SetSwapUsedIncompleteTile(bool used_incomplete_tile);
 
   // Notification from the OutputSurface that a swap has been consumed.
   void DidSwapBuffersComplete();
 
   int pending_swaps() const { return pending_swaps_; }
 
   // Indicates whether to prioritize impl thread latency (i.e., animation
   // smoothness) over new content activation.
-  void SetImplLatencyTakesPriority(bool impl_latency_takes_priority);
-  bool impl_latency_takes_priority() const {
-    return impl_latency_takes_priority_;
-  }
+  void SetSmoothnessMode(TreePriority tree_priority,
+                         ScrollHandlerState scroll_handler_state);
+
+  // Indicates if the main thread will likely respond within 1 vsync.
+  void SetCriticalBeginMainFrameToActivateIsFast(bool is_fast);
+
+  // A function of SetSmoothnessMode and
+  // SetCriticalBeginMainFrameToActivateIsFast.
+  bool ImplLatencyTakesPriority() const;
 
   // Indicates whether ACTION_DRAW_AND_SWAP_IF_POSSIBLE drew to the screen.
   void DidDrawIfPossibleCompleted(DrawResult result);
 
   // Indicates that a new begin main frame 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 SetNeedsBeginMainFrame();
   bool needs_begin_main_frame() const { return needs_begin_main_frame_; }
 
@@ skipping 116 matching lines @@
   bool needs_prepare_tiles_;
   bool needs_begin_main_frame_;
   bool needs_one_begin_impl_frame_;
   bool visible_;
   bool resourceless_draw_;
   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_;
+  TreePriority tree_priority_;
+  ScrollHandlerState scroll_handler_state_;
+  bool critical_begin_main_frame_to_activate_is_fast_;
   bool main_thread_missed_last_deadline_;
   bool skip_next_begin_main_frame_to_reduce_latency_;
   bool children_need_begin_frames_;
   bool defer_commits_;
   bool video_needs_begin_frames_;
   bool last_commit_had_no_updates_;
   bool wait_for_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_