Color the ink drop ripple and hover effects based on theming.

ui/views/animation/ink_drop_animation.h

 // Copyright 2016 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_ANIMATION_INK_DROP_ANIMATION_H_
 #define UI_VIEWS_ANIMATION_INK_DROP_ANIMATION_H_
 
 #include "base/macros.h"
-#include "base/observer_list.h"
 #include "ui/gfx/geometry/point.h"
 #include "ui/views/animation/ink_drop_animation_observer.h"
 #include "ui/views/animation/ink_drop_state.h"
 #include "ui/views/views_export.h"
 
 namespace ui {
 class Layer;
 }  // namespace ui
 
 namespace views {
 
 // Simple base class for animations that provide visual feedback for View state.
 // Manages the attached InkDropAnimationObservers.
 //
 // TODO(bruthig): Document the ink drop ripple on chromium.org and add a link to
 // the doc here.
 class VIEWS_EXPORT InkDropAnimation {
  public:
   // The opacity of the ink drop when it is not visible.
   static const float kHiddenOpacity;
 
   // The opacity of the ink drop when it is visible.
   static const float kVisibleOpacity;
 
   InkDropAnimation();
   virtual ~InkDropAnimation();
 
-  void AddObserver(InkDropAnimationObserver* observer);
-  void RemoveObserver(InkDropAnimationObserver* observer);
+  void set_observer(InkDropAnimationObserver* observer) {
+    observer_ = observer;
+  }
 
   // Gets the target InkDropState, i.e. the last |ink_drop_state| passed to
   // AnimateToState() or set by HideImmediately().
   virtual InkDropState GetTargetInkDropState() const = 0;
 
   // Animates from the current InkDropState to the new |ink_drop_state|.
   //
   // NOTE: GetTargetInkDropState() should return the new |ink_drop_state| value
   // to any observers being notified as a result of the call.
   virtual void AnimateToState(InkDropState ink_drop_state) = 0;
 
   // The root Layer that can be added in to a Layer tree.
   virtual ui::Layer* GetRootLayer() = 0;
 
   // Returns true when the ripple is visible. This is different from checking if
   // the ink_drop_state() == HIDDEN because the ripple may be visible while it
   // animates to the target HIDDEN state.
   virtual bool IsVisible() const = 0;
 
-  // Sets the |center_point| of the ink drop layer relative to its parent Layer.
-  virtual void SetCenterPoint(const gfx::Point& center_point) = 0;
-
   // Immediately aborts all in-progress animations and hides the ink drop.
   //
   // NOTE: This will NOT raise InkDropAnimation(Started|Ended) events for the
   // state transition to HIDDEN!
   virtual void HideImmediately() = 0;
 
  protected:
   // Notify the |observers_| that an animation has started.
   void NotifyAnimationStarted(InkDropState ink_drop_state);
 
   // Notify the |observers_| that an animation has ended.
   void NotifyAnimationEnded(
       InkDropState ink_drop_state,
       InkDropAnimationObserver::InkDropAnimationEndedReason reason);
 
  private:
-  // List of observers to notify when animations have started and finished.
-  base::ObserverList<InkDropAnimationObserver> observers_;
+  InkDropAnimationObserver* observer_;
 
   DISALLOW_COPY_AND_ASSIGN(InkDropAnimation);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_ANIMATION_INK_DROP_ANIMATION_H_