Refactor unreliable hit test code to avoid owning_layers

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 374 matching lines @@
   void UnregisterScrollbar(ScrollbarLayerImplBase* scrollbar_layer);
   ScrollbarSet ScrollbarsFor(int scroll_layer_id) const;
 
   void RegisterScrollLayer(LayerImpl* layer);
   void UnregisterScrollLayer(LayerImpl* layer);
 
   void AddSurfaceLayer(LayerImpl* layer);
   void RemoveSurfaceLayer(LayerImpl* layer);
   const LayerImplList& SurfaceLayers() const { return surface_layers_; }
 
-  LayerImpl* FindFirstScrollingLayerOrScrollbarLayerThatIsHitByPoint(
+  LayerImpl* FindFirstScrollingLayerOrDrawnScrollbarThatIsHitByPoint(
       const gfx::PointF& screen_space_point);
 
   LayerImpl* FindLayerThatIsHitByPoint(const gfx::PointF& screen_space_point);
 
   LayerImpl* FindLayerThatIsHitByPointInTouchHandlerRegion(
       const gfx::PointF& screen_space_point);
 
   void RegisterSelection(const LayerSelection& selection);
 
   bool GetAndResetHandleVisibilityChanged();
@@ skipping 156 matching lines @@
 
   std::unique_ptr<PendingPageScaleAnimation> pending_page_scale_animation_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(LayerTreeImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_IMPL_H_