Refactoring to make adding ink drop animations easier

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
new file mode 100644
index 0000000000000000000000000000000000000000..724949c7c44cb55319a24f4bc4d0692d93cdb7e9
--- /dev/null
+++ b/ui/views/animation/ink_drop_delegate.h
@@ -0,0 +1,32 @@
+// Copyright 2015 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_DELEGATE_H_
+#define UI_VIEWS_ANIMATION_INK_DROP_DELEGATE_H_
+
+#include "base/macros.h"
+#include "ui/views/views_export.h"
+
+namespace ui {
+class GestureEvent;
+}  // namespace ui
+
+namespace views {
+
+// .
+class VIEWS_EXPORT InkDropDelegate {
+ public:
+  InkDropDelegate() {}
+  virtual ~InkDropDelegate() {}
+
+  // ???
+  virtual void OnGestureEvent(ui::GestureEvent* event) = 0;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(InkDropDelegate);
+};
+
+}  // namespace views
+
+#endif  // UI_VIEWS_ANIMATION_INK_DROP_DELEGATE_H_