cc: Replace Region with SimpleEnclosedRegion for occlusion tracking

cc/layers/layer.h

 // Copyright 2010 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_LAYERS_LAYER_H_
 #define CC_LAYERS_LAYER_H_
 
 #include <set>
 #include <string>
 
@@ skipping 42 matching lines @@
 class LayerAnimationDelegate;
 class LayerAnimationEventObserver;
 class LayerClient;
 class LayerImpl;
 class LayerTreeHost;
 class LayerTreeImpl;
 class PriorityCalculator;
 class RenderingStatsInstrumentation;
 class ResourceUpdateQueue;
 class ScrollbarLayerInterface;
+class SimpleEnclosedRegion;
 struct AnimationEvent;
 template <typename LayerType>
 class OcclusionTracker;
 
 // Base class for composited layers. Special layer types are derived from
 // this class.
 class CC_EXPORT Layer : public base::RefCounted<Layer>,
                         public LayerAnimationValueObserver,
                         public LayerAnimationValueProvider {
  public:
@@ skipping 337 matching lines @@
     layer_animation_controller_->set_layer_animation_delegate(delegate);
   }
 
   bool HasActiveAnimation() const;
 
   void AddLayerAnimationEventObserver(
       LayerAnimationEventObserver* animation_observer);
   void RemoveLayerAnimationEventObserver(
       LayerAnimationEventObserver* animation_observer);
 
-  virtual Region VisibleContentOpaqueRegion() const;
+  virtual SimpleEnclosedRegion VisibleContentOpaqueRegion() const;
 
   virtual ScrollbarLayerInterface* ToScrollbarLayer();
 
   gfx::Rect LayerRectToContentRect(const gfx::RectF& layer_rect) const;
 
   virtual skia::RefPtr<SkPicture> GetPicture() const;
 
   // Constructs a LayerImpl of the correct runtime type for this Layer type.
   virtual scoped_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl);
 
@@ skipping 209 matching lines @@
   DrawProperties<Layer> draw_properties_;
 
   PaintProperties paint_properties_;
 
   DISALLOW_COPY_AND_ASSIGN(Layer);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_LAYER_H_