Enabled tests to control material design ink drop animations.

ui/views/animation/ink_drop_animation.h

Index: ui/views/animation/ink_drop_animation.h
diff --git a/ui/views/animation/ink_drop_animation.h b/ui/views/animation/ink_drop_animation.h
index 3d4c62fc97e8bccdc08abb1c4d9b6aa1fb2d0a3e..b00be7db26fe73f040ac80ff90eab1f046e4d849 100644
--- a/ui/views/animation/ink_drop_animation.h
+++ b/ui/views/animation/ink_drop_animation.h
@@ -19,6 +19,10 @@ class LayerAnimationObserver;
 
 namespace views {
 
+namespace test {
+class InkDropAnimationTestApi;
+}  // namespace test
+
 // Simple base class for animations that provide visual feedback for View state.
 // Manages the attached InkDropAnimationObservers.
 //
@@ -81,6 +85,11 @@ class VIEWS_EXPORT InkDropAnimation {
   // animates to the target HIDDEN state.
   virtual bool IsVisible() const = 0;
 
+  // Returns a test api to access internals of this. Default implmentations
+  // should return nullptr and test specific subclasses can override to return
+  // an instance.
+  virtual test::InkDropAnimationTestApi* GetTestApi();
+
  protected:
   // Animates the ripple from the |old_ink_drop_state| to the
   // |new_ink_drop_state|. |observer| is added to all LayerAnimationSequence's