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ui/compositor/compositor.h

 // Copyright (c) 2012 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 UI_COMPOSITOR_COMPOSITOR_H_
 #define UI_COMPOSITOR_COMPOSITOR_H_
 
 #include <string>
 
 #include "base/containers/hash_tables.h"
@@ skipping 123 matching lines @@
   Compositor(gfx::AcceleratedWidget widget,
              ui::ContextFactory* context_factory,
              scoped_refptr<base::SingleThreadTaskRunner> task_runner);
   virtual ~Compositor();
 
   ui::ContextFactory* context_factory() { return context_factory_; }
 
   // Schedules a redraw of the layer tree associated with this compositor.
   void ScheduleDraw();
 
+  // When set, this blocks all drawing operations. This can be used to keep
+  // what's currently in the buffer and stop drawing anything new for any period
+  // of time. Unblocking will schedule a redraw so that the buffer can catch up.
+  void SetBlockDrawing(bool block_drawing);
+
   // Sets the root of the layer tree drawn by this Compositor. The root layer
   // must have no parent. The compositor's root layer is reset if the root layer
   // is destroyed. NULL can be passed to reset the root layer, in which case the
   // compositor will stop drawing anything.
   // The Compositor does not own the root layer.
   const Layer* root_layer() const { return root_layer_; }
   Layer* root_layer() { return root_layer_; }
   void SetRootLayer(Layer* root_layer);
 
   // Called when we need the compositor to preserve the alpha channel in the
@@ skipping 145 matching lines @@
   int last_started_frame_;
   int last_ended_frame_;
 
   bool disable_schedule_composite_;
 
   CompositorLock* compositor_lock_;
 
   // Prevent more than one draw from being scheduled.
   bool defer_draw_scheduling_;
 
+  // Block all drawing
+  bool block_drawing_;
+
   // Used to prevent Draw()s while a composite is in progress.
   bool waiting_on_compositing_end_;
   bool draw_on_compositing_end_;
   enum SwapState { SWAP_NONE, SWAP_POSTED, SWAP_COMPLETED };
   SwapState swap_state_;
 
   LayerAnimatorCollection layer_animator_collection_;
 
   base::WeakPtrFactory<Compositor> schedule_draw_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Compositor);
 };
 
 }  // namespace ui
 
 #endif  // UI_COMPOSITOR_COMPOSITOR_H_