Address some bubble clipping issues

ui/views/view.cc

Index: ui/views/view.cc
diff --git a/ui/views/view.cc b/ui/views/view.cc
index 3580d046a375bf6b231976a4ef91827425f6302c..755f964541fec15be94ee98640deb0859d87fa61 100644
--- a/ui/views/view.cc
+++ b/ui/views/view.cc
@@ -808,12 +808,11 @@ void View::Paint(const ui::PaintContext& parent_context) {
     // 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.
-    gfx::Rect clip_rect_in_parent = bounds();
-    clip_rect_in_parent.Inset(clip_insets_);
-    if (parent_)
-      clip_rect_in_parent.set_x(
-          parent_->GetMirroredXForRect(clip_rect_in_parent));
-    clip_recorder.ClipRect(clip_rect_in_parent);
+    gfx::Path clip_path_in_parent = clip_path_;
+    if (clip_path_in_parent.isEmpty())
+      clip_path_in_parent.addRect(gfx::RectToSkRect(GetLocalBounds()));
+    clip_path_in_parent.offset(GetMirroredX(), y());
+    clip_recorder.ClipPathWithAntiAliasing(clip_path_in_parent);

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

I don't have a sense for how computationally expensive it is to use this versus
a boring old rectangle. I guess somewhere between "a bit" and "a lot". But do
you think it's worth only using path-based clipping when the |clip_path_| is
non-empty?  (e.g., it's probably fine for bubbles and SearchResultPageView to
use path-based clipping, but doing it for the general case might be
unnecessarily wasteful -- cc::ClipDisplayItem does seem like it has a lot of
custom codepaths for rectangles. In fact, there's even custom code in
ClipDisplayItem for *rounded* rectangles, but ClipRecorder::ClipRect always
passes an empty vector for the `SkRRect` argument.  Using
cc::clip*Path*DisplayItem would miss out on all that

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

I was hoping it would be smart, i.e. if the path is a rectangle there's no AA to
be done. But I guess it's no more LOC to explicitly use ClipRect in the unset
case.

   }
 
   ui::TransformRecorder transform_recorder(context);