Address some bubble clipping issues

ui/views/window/non_client_view.h

 // Copyright (c) 2012 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_WINDOW_NON_CLIENT_VIEW_H_
 #define UI_VIEWS_WINDOW_NON_CLIENT_VIEW_H_
 
 #include "base/macros.h"
 #include "ui/views/view.h"
 #include "ui/views/view_targeter_delegate.h"
@@ skipping 47 matching lines @@
                              int resize_corner_width,
                              bool can_resize);
 
   // Returns the bounds (in this View's parent's coordinates) that the client
   // view should be laid out within.
   virtual gfx::Rect GetBoundsForClientView() const = 0;
 
   virtual gfx::Rect GetWindowBoundsForClientBounds(
       const gfx::Rect& client_bounds) const = 0;
 
+  virtual bool GetClientMask(const gfx::Size& size,

[tapted, 2016/03/22 07:38:04]

I think this is kindof a nice abstraction (it should have a comment :), but
could BubbleFrameView::Layout() just call
GetWidget()->client_view()->set_clip_path(...); ? Maybe that's simpler, but
maybe it's also nice to have this as a method on NonClientFrameView, so it's
clear any NonClientFrameView can clip its ClientView - up to you (or sky/msw :)

[Evan Stade, 2016/03/22 17:59:58]

That approach is fine with me, but it requires BubbleFrameView::Layout() to have
a side effect outside of its own child hierarchy, which seems like some sort of
violation. I'll let sky/msw comment on which approach they prefer. Agreed that
this function needs a comment.

+                             gfx::Path* mask) const;
+
   // This function must ask the ClientView to do a hittest.  We don't do this in
   // the parent NonClientView because that makes it more difficult to calculate
   // hittests for regions that are partially obscured by the ClientView, e.g.
   // HTSYSMENU.
   // Return value is one of the windows HT constants (see ui/base/hit_test.h).
   virtual int NonClientHitTest(const gfx::Point& point) = 0;
 
   // Used to make the hosting widget shaped (non-rectangular). For a
   // rectangular window do nothing. For a shaped window update |window_mask|
   // accordingly. |size| is the size of the widget.
@@ skipping 179 matching lines @@
 
   // The accessible name of this view.
   base::string16 accessible_name_;
 
   DISALLOW_COPY_AND_ASSIGN(NonClientView);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WINDOW_NON_CLIENT_VIEW_H_