cc: Control activation from the Scheduler

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 55 matching lines @@
            commit_state_ == COMMIT_STATE_READY_TO_COMMIT;
   }
 
   bool RedrawPending() const { return needs_redraw_; }
 
   enum Action {
     ACTION_NONE,
     ACTION_SEND_BEGIN_FRAME_TO_MAIN_THREAD,
     ACTION_COMMIT,
     ACTION_UPDATE_VISIBLE_TILES,
-    ACTION_ACTIVATE_PENDING_TREE_IF_NEEDED,
+    ACTION_ACTIVATE_PENDING_TREE,
     ACTION_DRAW_IF_POSSIBLE,
     ACTION_DRAW_FORCED,
     ACTION_DRAW_AND_SWAP_ABORT,
     ACTION_BEGIN_OUTPUT_SURFACE_CREATION,
     ACTION_ACQUIRE_LAYER_TEXTURES_FOR_MAIN_THREAD,
   };
   static const char* ActionToString(Action action);
 
   scoped_ptr<base::Value> AsValue() const;
 
@@ skipping 59 matching lines @@
   void SetMainThreadNeedsLayerTextures();
 
   // Set that we can create the first OutputSurface and start the scheduler.
   void SetCanStart() { can_start_ = true; }
 
   // Indicates whether drawing would, at this time, make sense.
   // CanDraw can be used to supress flashes or checkerboarding
   // when such behavior would be undesirable.
   void SetCanDraw(bool can);
 
-  // Indicates whether or not there is a pending tree.  This influences
-  // whether or not we can succesfully commit at this time.  If the
+  // Indicates that the pending tree is ready for activation.
+  void NotifyReadyToActivate();
+
+  // Indicates whether or not there is a pending tree (which may be null)
+  // and whether the active tree is null or not.  This
+  // influences whether or not we can succesfully commit at this time.  If the
   // last commit is still being processed (but not blocking), it may not
   // be possible to take another commit yet.  This overrides force commit,
   // as a commit is already still in flight.
-  void SetHasPendingTree(bool has_pending_tree);
+  void SetHasTrees(bool has_pending_tree, bool active_tree_is_null_);
   bool has_pending_tree() const { return has_pending_tree_; }
 
   void DidLoseOutputSurface();
   void DidCreateAndInitializeOutputSurface();
   bool HasInitializedOutputSurface() const;
 
   // Exposed for testing purposes.
   void SetMaximumNumberOfFailedDrawsBeforeDrawIsForced(int num_draws);
 
   // True if we need to abort draws to make forward progress.
   bool PendingDrawsShouldBeAborted() const;
 
  protected:
   bool ShouldDrawForced() const;
   bool ShouldDraw() const;
-  bool ShouldAttemptTreeActivation() const;
+  bool ShouldActivatePendingTree() const;
   bool ShouldAcquireLayerTexturesForMainThread() const;
   bool ShouldUpdateVisibleTiles() const;
   bool ShouldSendBeginFrameToMainThread() const;
 
   bool HasDrawnThisFrame() const;
-  bool HasAttemptedTreeActivationThisFrame() const;
+  bool HasActivatedPendingTreeThisFrame() const;
   bool HasUpdatedVisibleTilesThisFrame() const;
   bool HasSentBeginFrameToMainThreadThisFrame() const;
 
   void HandleCommitInternal(bool commit_was_aborted);
   void UpdateStateOnDraw(bool did_swap);
 
   const SchedulerSettings settings_;
 
   OutputSurfaceState output_surface_state_;
   CommitState commit_state_;
 
   int commit_count_;
   int current_frame_number_;
   int last_frame_number_where_begin_frame_sent_to_main_thread_;
   int last_frame_number_where_draw_was_called_;
-  int last_frame_number_where_tree_activation_attempted_;
+  int last_frame_number_pending_tree_activated_;
   int last_frame_number_where_update_visible_tiles_was_called_;
   int consecutive_failed_draws_;
   int maximum_number_of_failed_draws_before_draw_is_forced_;
   bool needs_redraw_;
   bool swap_used_incomplete_tile_;
   bool needs_forced_redraw_;
   bool needs_forced_redraw_after_next_commit_;
   bool needs_commit_;
   bool needs_forced_commit_;
   bool expect_immediate_begin_frame_for_main_thread_;
   bool main_thread_needs_layer_textures_;
   bool inside_begin_frame_;
   BeginFrameArgs last_begin_frame_args_;
+  bool active_tree_has_been_drawn_;
+  bool active_tree_is_null_;
   bool visible_;
   bool can_start_;
   bool can_draw_;
   bool has_pending_tree_;
+  bool pending_tree_is_ready_for_activation_;
   bool draw_if_possible_failed_;
   TextureState texture_state_;
   bool did_create_and_initialize_first_output_surface_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SchedulerStateMachine);
 };
 
 }  // namespace cc
 
 #endif  // CC_SCHEDULER_SCHEDULER_STATE_MACHINE_H_