Enhance the material design ripple API so the ripple's state can be controlled by it's owning View.

ui/views/animation/ink_drop_host.h

+// 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_HOST_H_
+#define UI_VIEWS_ANIMATION_INK_DROP_HOST_H_
+
+#include "base/macros.h"
+#include "ui/views/views_export.h"
+
+namespace ui {
+class Layer;
+}  // namespace ui
+
+namespace views {
+
+// Used by the InkDropAnimationController to add and remove the ink drop layers
+// from a host's layer tree. Typically the ink drop layer is added to a View's
+// layer but it can also be added to a View's ancestor layer.
+//
+// Note: Some Views do not own a Layer, but you can use
+// View::SetLayer(new ui::Layer(ui::LAYER_NOT_DRAWN)) to force the View to have
+// a lightweight Layer that can parent the ink drop layer.
+class VIEWS_EXPORT InkDropHost {
+ public:
+  InkDropHost() {}
+  virtual ~InkDropHost() {}
+
+  // Add the |ink_drop_layer| in to a visible layer tree.
+  virtual void AddInkDropLayer(ui::Layer* ink_drop_layer) = 0;
+
+  // Removes |ink_drop_layer| from the layer tree.
+  virtual void RemoveInkDropLayer(ui::Layer* ink_drop_layer) = 0;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(InkDropHost);
+};
+
+}  // namespace views
+
+#endif  // UI_VIEWS_ANIMATION_INK_DROP_HOST_H_