Implement MD simple gesture nav

content/browser/web_contents/aura/gesture_nav_simple.h

Index: content/browser/web_contents/aura/gesture_nav_simple.h
diff --git a/content/browser/web_contents/aura/gesture_nav_simple.h b/content/browser/web_contents/aura/gesture_nav_simple.h
index d2c593701aec4f89bd6eb7349fb539d206bcef8f..44dc2b628b3ac9102dc0f84a51d68f0a2a1e6268 100644
--- a/content/browser/web_contents/aura/gesture_nav_simple.h
+++ b/content/browser/web_contents/aura/gesture_nav_simple.h
@@ -10,17 +10,8 @@
 #include "base/macros.h"
 #include "content/browser/renderer_host/overscroll_controller_delegate.h"
 
-namespace gfx {
-class Transform;
-}
-
-namespace ui {
-class Layer;
-}
-
 namespace content {
 
-class ArrowLayerDelegate;
 class WebContentsImpl;
 
 // A simple delegate for the overscroll controller that paints an arrow on top
@@ -31,23 +22,20 @@ class GestureNavSimple : public OverscrollControllerDelegate {
   ~GestureNavSimple() override;
 
  private:
-  void ApplyEffectsAndDestroy(const gfx::Transform& transform, float opacity);
+  class Affordance;
+
   void AbortGestureAnimation();
   void CompleteGestureAnimation();
-  bool ApplyEffectsForDelta(float delta_x);
 
   // OverscrollControllerDelegate:
   gfx::Rect GetVisibleBounds() const override;
-  // Returns true if the scroll update was consumed.
   bool OnOverscrollUpdate(float delta_x, float delta_y) override;
   void OnOverscrollComplete(OverscrollMode overscroll_mode) override;
   void OnOverscrollModeChange(OverscrollMode old_mode,
                               OverscrollMode new_mode) override;
 
   WebContentsImpl* web_contents_;
-  std::unique_ptr<ui::Layer> clip_layer_;
-  std::unique_ptr<ui::Layer> arrow_;
-  std::unique_ptr<ArrowLayerDelegate> arrow_delegate_;
+  std::unique_ptr<Affordance> affordance_;
   float completion_threshold_;
 
   DISALLOW_COPY_AND_ASSIGN(GestureNavSimple);