Ensure that mask layer is of the same size as the owning layer.

ui/views/bubble/bubble_dialog_delegate.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_BUBBLE_BUBBLE_DIALOG_DELEGATE_H_
 #define UI_VIEWS_BUBBLE_BUBBLE_DIALOG_DELEGATE_H_
 
 #include <memory>
 
 #include "base/gtest_prod_util.h"
@@ skipping 130 matching lines @@
   virtual void Init();
 
   // Sets the anchor view or rect and repositions the bubble. Note that if a
   // valid view gets passed, the anchor rect will get ignored. If the view gets
   // deleted, but no new view gets set, the last known anchor postion will get
   // returned.
   void SetAnchorView(View* anchor_view);
   void SetAnchorRect(const gfx::Rect& rect);
 
   // Resize and potentially move the bubble to fit the content's preferred size.
-  void SizeToContents();
+  virtual void SizeToContents();
 
   BubbleFrameView* GetBubbleFrameView() const;
 
  private:
   friend class BubbleBorderDelegate;
   friend class BubbleWindowTargeter;
 
   FRIEND_TEST_ALL_PREFIXES(BubbleDelegateTest, CreateDelegate);
   FRIEND_TEST_ALL_PREFIXES(BubbleDelegateTest, NonClientHitTest);
 
@@ skipping 47 matching lines @@
 
   // Parent native window of the bubble.
   gfx::NativeView parent_window_;
 
   DISALLOW_COPY_AND_ASSIGN(BubbleDialogDelegateView);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_BUBBLE_BUBBLE_DELEGATE2_H_