Adding ripple effect for clicks on MD slider

ui/views/controls/slider.h

 // Copyright (c) 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 UI_VIEWS_CONTROLS_SLIDER_H_
 #define UI_VIEWS_CONTROLS_SLIDER_H_
 
 #include "base/macros.h"
 #include "ui/gfx/animation/animation_delegate.h"
 #include "ui/views/view.h"
@@ skipping 59 matching lines @@
 
   // Update UI based on control on/off state.
   virtual void UpdateState(bool control_on) = 0;
 
  protected:
   explicit Slider(SliderListener* listener);
 
   // Returns the current position of the thumb on the slider.
   float GetAnimatingValue() const;
 
+  // Shows or hides the highlight on the slider thumb. The default
+  // implementation does nothing.
+  virtual void SetHighlighted(bool is_highlighted);
+
+  // Gets the size of the slider's thumb.
   virtual int GetThumbWidth() = 0;
 
   // views::View:
   void OnPaint(gfx::Canvas* canvas) override;
 
+  // gfx::AnimationDelegate:
+  void AnimationProgressed(const gfx::Animation* animation) override;
+  void AnimationEnded(const gfx::Animation* animation) override;
+
  private:
   friend class test::SliderTestApi;
 
   void SetValueInternal(float value, SliderChangeReason reason);
 
   // Should be called on the Mouse Down event. Used to calculate relative
   // position of the mouse cursor (or the touch point) on the button to
   // accurately move the button using the MoveButtonTo() method.
   void PrepareForMove(const int new_x);
 
@@ skipping 15 matching lines @@
   bool OnMouseDragged(const ui::MouseEvent& event) override;
   void OnMouseReleased(const ui::MouseEvent& event) override;
   bool OnKeyPressed(const ui::KeyEvent& event) override;
   void GetAccessibleState(ui::AXViewState* state) override;
   void OnFocus() override;
   void OnBlur() override;
 
   // ui::EventHandler:
   void OnGestureEvent(ui::GestureEvent* event) override;
 
-  // gfx::AnimationDelegate:
-  void AnimationProgressed(const gfx::Animation* animation) override;
-
   void set_listener(SliderListener* listener) {
     listener_ = listener;
   }
 
   SliderListener* listener_;
 
   std::unique_ptr<gfx::SlideAnimation> move_animation_;
 
   float value_;
   float keyboard_increment_;
-  float animating_value_;
+  float initial_animating_value_;
   bool value_is_valid_;
   base::string16 accessible_name_;
   bool accessibility_events_enabled_;
   SkColor focus_border_color_;
 
   // Relative position of the mouse cursor (or the touch point) on the slider's
   // button.
   int initial_button_offset_;
 
   DISALLOW_COPY_AND_ASSIGN(Slider);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_SLIDER_H_