Add ink drop masking to TrayBackgroundView

ui/views/animation/ink_drop.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_H_
 #define UI_VIEWS_ANIMATION_INK_DROP_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "base/time/time.h"
 #include "ui/compositor/layer_tree_owner.h"
 #include "ui/events/event_handler.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/size.h"
 #include "ui/views/animation/ink_drop_state.h"
 #include "ui/views/views_export.h"
 
 namespace views {
 
 // Pure virtual base class that manages the lifetime and state of an ink drop
 // ripple as well as visual hover state feedback.
 class VIEWS_EXPORT InkDrop {
  public:
   virtual ~InkDrop() {}
 
+  // Used to update the layer size for the ink drop.
+  virtual void UpdateLayerSize(const gfx::Size& layer_size) = 0;

[bruthig, 2016/11/14 19:09:38]

I think this would be better named as "HostSizeChanged()".  Client's shouldn't
need to be aware about the underlying Layer or it's size. And the docs should
tell clients when it needs to be called.

[mohsen, 2016/11/14 20:19:39]

Sure. Done.

+
   // Gets the target state of the ink drop.
   virtual InkDropState GetTargetInkDropState() const = 0;
 
   // Animates from the current InkDropState to |ink_drop_state|.
   virtual void AnimateToState(InkDropState ink_drop_state) = 0;
 
   // Immediately snaps the InkDropState to ACTIVATED. This more specific
   // implementation of the non-existent SnapToState(InkDropState) function is
   // the only one available because it was the only InkDropState that clients
   // needed to skip animations for.
   virtual void SnapToActivated() = 0;
 
   // Enables or disables the hover state.
   virtual void SetHovered(bool is_hovered) = 0;
 
   // Enables or disables the focus state.
   virtual void SetFocused(bool is_focused) = 0;
 
  protected:
   InkDrop() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(InkDrop);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_ANIMATION_INK_DROP_H_