Add MD Ink Drop to host only when a ripple/hover is active.

ui/views/animation/ink_drop_animation_controller_impl.h

Index: ui/views/animation/ink_drop_animation_controller_impl.h
diff --git a/ui/views/animation/ink_drop_animation_controller_impl.h b/ui/views/animation/ink_drop_animation_controller_impl.h
index 5769c3bdcf0f6400f3384c99de1b9db0f217a228..f39e4b9dd8a56bb793dfa9e14f937e30daa1320d 100644
--- a/ui/views/animation/ink_drop_animation_controller_impl.h
+++ b/ui/views/animation/ink_drop_animation_controller_impl.h
@@ -11,6 +11,7 @@
 #include "ui/gfx/geometry/size.h"
 #include "ui/views/animation/ink_drop_animation_controller.h"
 #include "ui/views/animation/ink_drop_animation_observer.h"
+#include "ui/views/animation/ink_drop_hover_observer.h"
 #include "ui/views/views_export.h"
 
 namespace base {
@@ -30,7 +31,8 @@ class InkDropAnimationControllerFactoryTest;
 // A functional implementation of an InkDropAnimationController.
 class VIEWS_EXPORT InkDropAnimationControllerImpl
     : public InkDropAnimationController,
-      public InkDropAnimationObserver {
+      public InkDropAnimationObserver,
+      public InkDropHoverObserver {
  public:
   // Constructs an ink drop controller that will attach the ink drop to the
   // given |ink_drop_host|.
@@ -65,6 +67,14 @@ class VIEWS_EXPORT InkDropAnimationControllerImpl
   // Destroys the current |hover_|.
   void DestroyInkDropHover();
 
+  // Adds the |root_layer_| to the |ink_drop_host_| if it hasn't already been
+  // added.
+  void AddRootLayerToHostIfNeeded();
+
+  // Removes the |root_layer_| from the |ink_drop_host_| if no ink drop ripple
+  // or hover is active.
+  void RemoveRootLayerFromHostIfNeeded();
+
   // Returns true if the hover animation is in the process of fading in or
   // is visible.
   bool IsHoverFadingInOrVisible() const;
@@ -74,6 +84,11 @@ class VIEWS_EXPORT InkDropAnimationControllerImpl
   void AnimationEnded(InkDropState ink_drop_state,
                       InkDropAnimationEndedReason reason) override;
 
+  // views::InkDropHoverObserver:
+  void AnimationStarted(InkDropHover::AnimationType animation_type) override;
+  void AnimationEnded(InkDropHover::AnimationType animation_type,
+                      InkDropAnimationEndedReason reason) override;
+
   // Enables or disables the hover state based on |is_hovered| and if an
   // animation is triggered it will be scheduled to have the given
   // |animation_duration|. If |explode| is true the hover will expand as it
@@ -101,6 +116,9 @@ class VIEWS_EXPORT InkDropAnimationControllerImpl
   // from the InkDropHost.
   scoped_ptr<ui::Layer> root_layer_;
 
+  // True when the |root_layer_| has been added to the |ink_drop_host_|.
+  bool root_layer_added_to_host_;
+
   // The current InkDropHover. Lazily created using CreateInkDropHover();
   scoped_ptr<InkDropHover> hover_;