android: Use UIResource for overscroll glow

content/browser/android/edge_effect.h

 // Copyright (c) 2013 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 CONTENT_BROWSER_ANDROID_EDGE_EFFECT_H_
 #define CONTENT_BROWSER_ANDROID_EDGE_EFFECT_H_
 
 #include "base/basictypes.h"
-#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/time/time.h"
 #include "ui/gfx/size_f.h"
 
 namespace cc {
 class Layer;
 }
 
 namespace content {
 
 /* |EdgeEffect| mirrors its Android counterpart, EdgeEffect.java.
  * The primary difference is ownership; the Android version manages render
  * resources directly, while this version simply applies the effect to
  * existing resources. Conscious tradeoffs were made to align this as closely
  * as possible with the original Android java version.
  * All coordinates and dimensions are in device pixels.
  */
 class EdgeEffect {
-public:
+ public:
+  // A wrapper class over the cc::Layer.
+  class LayerWrapper {
+   public:
+    virtual cc::Layer* layer() = 0;
+    virtual ~LayerWrapper() {}
+  };
+
   enum Edge {
     EDGE_TOP = 0,
     EDGE_LEFT,
     EDGE_BOTTOM,
     EDGE_RIGHT,
     EDGE_COUNT
   };
 
-  EdgeEffect(scoped_refptr<cc::Layer> edge, scoped_refptr<cc::Layer> glow);
+  EdgeEffect(scoped_ptr<LayerWrapper> edge, scoped_ptr<LayerWrapper> glow);
   ~EdgeEffect();
 
   void Pull(base::TimeTicks current_time, float delta_distance);
   void Absorb(base::TimeTicks current_time, float velocity);
   bool Update(base::TimeTicks current_time);
   void Release(base::TimeTicks current_time);
 
   void Finish();
   bool IsFinished() const;
 
   void ApplyToLayers(gfx::SizeF window_size,
                      Edge edge,
                      float edge_height,
                      float glow_height,
                      float offset);
 
 private:
 
   enum State {
     STATE_IDLE = 0,
     STATE_PULL,
     STATE_ABSORB,
     STATE_RECEDE,
     STATE_PULL_DECAY
   };
 
-  scoped_refptr<cc::Layer> edge_;
-  scoped_refptr<cc::Layer> glow_;
+  scoped_ptr<LayerWrapper> edge_;
+  scoped_ptr<LayerWrapper> glow_;
 
   float edge_alpha_;
   float edge_scale_y_;
   float glow_alpha_;
   float glow_scale_y_;
 
   float edge_alpha_start_;
   float edge_alpha_finish_;
   float edge_scale_y_start_;
   float edge_scale_y_finish_;
   float glow_alpha_start_;
   float glow_alpha_finish_;
   float glow_scale_y_start_;
   float glow_scale_y_finish_;
 
   base::TimeTicks start_time_;
   base::TimeDelta duration_;
 
   State state_;
 
   float pull_distance_;
 
   DISALLOW_COPY_AND_ASSIGN(EdgeEffect);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_ANDROID_EDGE_EFFECT_H_