Add ink drop masking to TrayBackgroundView

ui/views/animation/test/test_ink_drop.h

 // Copyright 2016 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_TEST_INK_DROP_H_
 #define UI_VIEWS_ANIMATION_TEST_INK_DROP_H_
 
 #include "ui/views/animation/ink_drop.h"
 
 namespace views {
 namespace test {
 
 // A InkDrop test double that tracks the last requested state changes.
 //
 // NOTE: This does not auto transition between any of the InkDropStates.
 //
 class TestInkDrop : public InkDrop {
  public:
   TestInkDrop();
   ~TestInkDrop() override;
 
   bool is_hovered() const { return is_hovered_; }
 
+  void HostSizeChanged(const gfx::Size& new_size) override;
   InkDropState GetTargetInkDropState() const override;
   void AnimateToState(InkDropState ink_drop_state) override;
   void SnapToActivated() override;
   void SetHovered(bool is_hovered) override;
   void SetFocused(bool is_focused) override;
 
  private:
   InkDropState state_;
   bool is_hovered_;
 
   DISALLOW_COPY_AND_ASSIGN(TestInkDrop);
 };
 
 }  // namespace test
 }  // namespace views
 
 #endif  // UI_VIEWS_ANIMATION_TEST_INK_DROP_H_