Added material design mouse hover feedback support.

ui/views/animation/ink_drop_delegate.h

Index: ui/views/animation/ink_drop_delegate.h
diff --git a/ui/views/animation/ink_drop_delegate.h b/ui/views/animation/ink_drop_delegate.h
index 576b742a610b989a570245275a1b53bbe2fb709d..0bf265aeb3caee5e8ca8603589f8255ed9d60a1f 100644
--- a/ui/views/animation/ink_drop_delegate.h
+++ b/ui/views/animation/ink_drop_delegate.h
@@ -42,6 +42,9 @@ class VIEWS_EXPORT InkDropDelegate {
   // as well as a NONE value.
   virtual void OnAction(InkDropState state) = 0;
 
+  // Enables or disables the hover state.
+  virtual void SetHovered(bool is_hovered) = 0;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(InkDropDelegate);
 };