cc: Split Proxy to eliminate unnecessary dependencies on the impl side

cc/trees/layer_tree_impl.h

 // Copyright 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 CC_TREES_LAYER_TREE_IMPL_H_
 #define CC_TREES_LAYER_TREE_IMPL_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 26 matching lines @@
 class HeadsUpDisplayLayerImpl;
 class LayerExternalScrollOffsetListener;
 class LayerScrollOffsetDelegate;
 class LayerTreeDebugState;
 class LayerTreeImpl;
 class LayerTreeSettings;
 class MemoryHistory;
 class OutputSurface;
 class PageScaleAnimation;
 class PictureLayerImpl;
-class Proxy;
+class ThreadVerifier;
 class ResourceProvider;
 class TileManager;
 class UIResourceRequest;
 class VideoFrameControllerClient;
 struct PendingPageScaleAnimation;
 struct RendererCapabilities;
 
 typedef std::vector<UIResourceRequest> UIResourceRequestQueue;
 typedef SyncedProperty<AdditionGroup<float>> SyncedTopControls;
 typedef SyncedProperty<AdditionGroup<gfx::Vector2dF>> SyncedElasticOverscroll;
@@ skipping 41 matching lines @@
   gfx::Rect DeviceViewport() const;
   gfx::Size DrawViewportSize() const;
   const gfx::Rect ViewportRectForTilePriority() const;
   scoped_ptr<ScrollbarAnimationController> CreateScrollbarAnimationController(
       int scroll_layer_id);
   void DidAnimateScrollOffset();
   void InputScrollAnimationFinished();
   bool use_gpu_rasterization() const;
   GpuRasterizationStatus GetGpuRasterizationStatus() const;
   bool create_low_res_tiling() const;
   BlockingTaskRunner* BlockingMainThreadTaskRunner() const;

[vmpstr, 2015/10/16 18:42:25]

I think this function can go if you just have a task_runner_provider()

then 
layer_tree()->BlockingMainThreadTaskRunner()
becomes
layer_tree()->task_runner_provider()->blocking_main_thread_task_runner()

[Khushal, 2015/10/17 00:06:30]

Done.

   bool RequiresHighResToDraw() const;
   bool SmoothnessTakesPriority() const;
   VideoFrameControllerClient* GetVideoFrameControllerClient() const;
 
   // Tree specific methods exposed to layer-impl tree.
   // ---------------------------------------------------------------------------
   void SetNeedsRedraw();
 
   // Tracing methods.
   // ---------------------------------------------------------------------------
@@ skipping 139 matching lines @@
   AnimationRegistrar* GetAnimationRegistrar() const;
 
   void DidBecomeActive();
 
   // Set on the active tree when the viewport size recently changed
   // and the active tree's size is now out of date.
   bool ViewportSizeInvalid() const;
   void SetViewportSizeInvalid();
   void ResetViewportSizeInvalid();
 
   // Useful for debug assertions, probably shouldn't be used for anything else.

[vmpstr, 2015/10/16 18:42:25]

I think this comment is a lie, since we use this to get a blocking main thread
runner. 

[Khushal, 2015/10/17 00:06:30]

Done. Changed it to be more accurate.

-  Proxy* proxy() const;
+  ThreadVerifier* thread_verifier() const;
 
   // Distribute the root scroll between outer and inner viewport scroll layer.
   // The outer viewport scroll layer scrolls first.
   void DistributeRootScrollOffset(const gfx::ScrollOffset& root_offset);
 
   void ApplyScroll(LayerImpl* layer, ScrollState* scroll_state) {
     layer_tree_host_impl_->ApplyScroll(layer, scroll_state);
   }
 
   // Call this function when you expect there to be a swap buffer.
@@ skipping 213 matching lines @@
 
   scoped_ptr<PendingPageScaleAnimation> pending_page_scale_animation_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(LayerTreeImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_IMPL_H_