cc: Consider Surface active if frame received recently

cc/surfaces/display_scheduler.h

Index: cc/surfaces/display_scheduler.h
diff --git a/cc/surfaces/display_scheduler.h b/cc/surfaces/display_scheduler.h
index bc509c7b1caa080107b07c9e2bbeb63bbea8a931..b4005210d5e0c387ad30d93c95679948d37fd169 100644
--- a/cc/surfaces/display_scheduler.h
+++ b/cc/surfaces/display_scheduler.h
@@ -54,6 +54,11 @@ class CC_SURFACES_EXPORT DisplayScheduler : public BeginFrameObserverBase {
   void OnBeginFrameDeadline();
   void DrawAndSwap();
 
+  std::set<SurfaceId>& CurrentActiveChildSurfaceIDs();
+  void UpdateFutureActiveChildSurfaceIDs(SurfaceId surface_id);
+  void ClearActiveSurfaces();
+  void UpdateActiveSurfaces();
+
   DisplaySchedulerClient* client_;
   BeginFrameSource* begin_frame_source_;
   base::SingleThreadTaskRunner* task_runner_;
@@ -76,11 +81,12 @@ class CC_SURFACES_EXPORT DisplayScheduler : public BeginFrameObserverBase {
 
   SurfaceId root_surface_id_;
   bool root_surface_damaged_;
-  bool expect_damage_from_root_surface_;
+  bool root_surface_active_;
 
+  static const int kActiveChildSurfaceIdsSize = 3;

[sunnyps, 2015/07/23 21:10:38]

nit: kNumFramesSurfaceIsActive?

[brianderson, 2015/07/23 22:21:49]

Done.

   std::set<SurfaceId> child_surface_ids_damaged_;
-  std::set<SurfaceId> child_surface_ids_damaged_prev_;
-  std::vector<SurfaceId> child_surface_ids_to_expect_damage_from_;
+  std::set<SurfaceId> active_child_surface_ids_[kActiveChildSurfaceIdsSize];
+  int current_active_child_surface_ids_index_;
 
   base::WeakPtrFactory<DisplayScheduler> weak_ptr_factory_;