cc: Drop ContextProvider references on the impl thread before quitting

cc/trees/layer_tree_host_impl.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_TREES_LAYER_TREE_HOST_IMPL_H_
 #define CC_TREES_LAYER_TREE_HOST_IMPL_H_
 
 #include <list>
 #include <string>
 #include <vector>
@@ skipping 28 matching lines @@
 class DebugRectHistory;
 class FrameRateCounter;
 class LayerImpl;
 class LayerTreeHostImplTimeSourceAdapter;
 class LayerTreeImpl;
 class PageScaleAnimation;
 class PaintTimeCounter;
 class MemoryHistory;
 class RenderingStatsInstrumentation;
 class RenderPassDrawQuad;
+class TextureMailboxDeleter;
 class TopControlsManager;
 class UIResourceBitmap;
 struct RendererCapabilities;
 struct UIResourceRequest;
 
 // LayerTreeHost->Proxy callback interface.
 class LayerTreeHostImplClient {
  public:
   virtual void DidLoseOutputSurfaceOnImplThread() = 0;
   virtual void OnSwapBuffersCompleteOnImplThread() = 0;
@@ skipping 472 matching lines @@
   scoped_ptr<PageScaleAnimation> page_scale_animation_;
 
   // This is used for ticking animations slowly when hidden.
   scoped_ptr<LayerTreeHostImplTimeSourceAdapter> time_source_client_adapter_;
 
   scoped_ptr<FrameRateCounter> fps_counter_;
   scoped_ptr<PaintTimeCounter> paint_time_counter_;
   scoped_ptr<MemoryHistory> memory_history_;
   scoped_ptr<DebugRectHistory> debug_rect_history_;
 
+  scoped_ptr<TextureMailboxDeleter> texture_mailbox_deleter_;
+
   // The maximum memory that would be used by the prioritized resource
   // manager, if there were no limit on memory usage.
   size_t max_memory_needed_bytes_;
 
   size_t last_sent_memory_visible_bytes_;
   size_t last_sent_memory_visible_and_nearby_bytes_;
   size_t last_sent_memory_use_bytes_;
   bool zero_budget_;
 
   // Viewport size passed in from the main thread, in physical pixels.  This
@@ skipping 43 matching lines @@
 
   // Optional callback to notify of new tree activations.
   base::Closure tree_activation_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHostImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_IMPL_H_