Fix bubble client area clipping regression.

ui/views/view.cc

 // 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.
 
 #define _USE_MATH_DEFINES // For VC++ to get M_PI. This has to be first.
 
 #include "ui/views/view.h"
 
 #include <algorithm>
 #include <cmath>
@@ skipping 795 matching lines @@
   if (paint_relative_to_parent) {
     // Set the clip rect to the bounds of this View, or |clip_path_| if it's
     // been set. Note that the X (or left) position we pass to ClipRect takes
     // into consideration whether or not the View uses a right-to-left layout so
     // that we paint the View in its mirrored position if need be.
     if (clip_path_.isEmpty()) {
       clip_recorder.ClipRect(GetMirroredBounds());
     } else {
       gfx::Path clip_path_in_parent = clip_path_;
       clip_path_in_parent.offset(GetMirroredX(), y());
-      clip_recorder.ClipPath(clip_path_in_parent);
+      clip_recorder.ClipPathWithAntiAliasing(clip_path_in_parent);

[Evan Stade, 2016/03/29 01:27:58]

I tried to avoid this before and instead inset by 0.5 for perf reasons, but as
the bug(s) point out, this doesn't work.

[msw, 2016/03/29 23:08:27]

Maybe add a comment about why the aa is needed here?

[Evan Stade, 2016/03/29 23:11:52]

Do you have a suggestion for a good comment? It seems to boil down to "the clip
path could have partially transparent pixels, so use AA" but that seems sort of
self evident (as in, that's the only reason you'd use AA to begin with).

[msw, 2016/03/29 23:19:13]

Shrug, I don't understand why it would have transparent pixels now, but not
before this change... shouldn't the round rect corners yield some mid-pixel
paths regardless of your old 0.5f extra inset? I dunno, I suppose it might be
self-evident to people more familiar with clip paths than myself.

     }
   }
 
   ui::TransformRecorder transform_recorder(context);
   if (paint_relative_to_parent) {
     // Translate the graphics such that 0,0 corresponds to where
     // this View is located relative to its parent.
     gfx::Transform transform_from_parent;
     gfx::Vector2d offset_from_parent = GetMirroredPosition().OffsetFromOrigin();
     transform_from_parent.Translate(offset_from_parent.x(),
@@ skipping 1598 matching lines @@
   // Message the RootView to do the drag and drop. That way if we're removed
   // the RootView can detect it and avoid calling us back.
   gfx::Point widget_location(event.location());
   ConvertPointToWidget(this, &widget_location);
   widget->RunShellDrag(this, data, widget_location, drag_operations, source);
   // WARNING: we may have been deleted.
   return true;
 }
 
 }  // namespace views