Add ink drop masking to TrayBackgroundView

ui/views/animation/ink_drop_mask.h

Index: ui/views/animation/ink_drop_mask.h
diff --git a/ui/views/animation/ink_drop_mask.h b/ui/views/animation/ink_drop_mask.h
new file mode 100644
index 0000000000000000000000000000000000000000..2e1b91a20d2c351da19767ca0d94a8ebb3d1a91a
--- /dev/null
+++ b/ui/views/animation/ink_drop_mask.h
@@ -0,0 +1,75 @@
+// 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_INK_DROP_MASK_H_
+#define UI_VIEWS_ANIMATION_INK_DROP_MASK_H_
+
+#include "base/macros.h"
+#include "ui/compositor/layer.h"
+#include "ui/compositor/layer_delegate.h"
+#include "ui/gfx/geometry/point.h"
+#include "ui/gfx/geometry/rect.h"
+#include "ui/views/views_export.h"
+
+namespace views {
+
+// Base class for different ink drop masks. It is responsible for creating the
+// ui::Layer that can be set as the mask layer for ink drop layer.
+class VIEWS_EXPORT InkDropMask : public ui::LayerDelegate {
+ public:
+  ~InkDropMask() override;
+
+  ui::Layer* layer() { return &layer_; }
+
+ protected:
+  explicit InkDropMask(const gfx::Rect& layer_bounds);
+
+ private:
+  // Overriden from ui::LayerDelegate:
+  void OnDelegatedFrameDamage(const gfx::Rect& damage_rect_in_dip) override;
+
+  void OnDeviceScaleFactorChanged(float device_scale_factor) override;
+
+  ui::Layer layer_;
+
+  DISALLOW_COPY_AND_ASSIGN(InkDropMask);
+};
+
+// A rectangular ink drop mask with rounded corners.
+class VIEWS_EXPORT RoundRectInkDropMask : public InkDropMask {
+ public:
+  RoundRectInkDropMask(const gfx::Rect& layer_bounds,
+                       const gfx::Rect& mask_bounds,
+                       int corner_radius);
+
+ private:
+  // Overriden from InkDropMask:
+  void OnPaintLayer(const ui::PaintContext& context) override;
+
+  gfx::Rect mask_bounds_;
+  int corner_radius_;
+
+  DISALLOW_COPY_AND_ASSIGN(RoundRectInkDropMask);
+};
+
+// A circular ink drop mask.
+class VIEWS_EXPORT CircleInkDropMask : public InkDropMask {
+ public:
+  CircleInkDropMask(const gfx::Rect& layer_bounds,
+                    const gfx::Point& mask_center,
+                    int mask_radius);
+
+ private:
+  // Overriden from InkDropMask:
+  void OnPaintLayer(const ui::PaintContext& context) override;
+
+  gfx::Point mask_center_;
+  int mask_radius_;
+
+  DISALLOW_COPY_AND_ASSIGN(CircleInkDropMask);
+};
+
+}  // namespace views
+
+#endif  // UI_VIEWS_ANIMATION_INK_DROP_MASK_H_