MacViews: Add native drop shadow to dialogs on OSX < 10.10.

ui/views/bubble/bubble_border.h

Index: ui/views/bubble/bubble_border.h
diff --git a/ui/views/bubble/bubble_border.h b/ui/views/bubble/bubble_border.h
index fac3a719a474b9771fda692b4fad20bfb99a868c..2aff6de66af9744dbf0f3f3f56fab26f67637442 100644
--- a/ui/views/bubble/bubble_border.h
+++ b/ui/views/bubble/bubble_border.h
@@ -15,8 +15,11 @@
 
 namespace gfx {
 class Rect;
+class Path;
 }
 
+class SkPath;
+
 namespace views {
 class Painter;
 
@@ -204,6 +207,12 @@ class VIEWS_EXPORT BubbleBorder : public Border {
   // Gets the arrow offset to use.
   int GetArrowOffset(const gfx::Size& border_size) const;
 
+  // Returns the arrow mask/path given |view_bounds|. |view_bounds| should be in
+  // it's own coordinates(i.e. with origin at (0,0)). An empty mask is returned

[tapted, 2016/01/28 05:59:22]

nit: it's -> its, `coordinates(i.e. with origin at..` -> `coordinates (origin
at..`

An empty mask.. -> |path| is unchanged if there is no painted arrow.

[karandeepb, 2016/02/04 03:39:27]

Done.

+  // in case the border doesn't have an arrow or the arrow paint type is not
+  // PAINT_NORMAL.
+  void GetArrowMask(const gfx::Rect& view_bounds, gfx::Path* mask) const;

[tapted, 2016/01/28 05:59:22]

I think GetArrowPath is a better name for it, since it's usually used for
drawing, not clipping (whereas 'mask' is typically just clipping). then mask ->
path.

[karandeepb, 2016/02/04 03:39:28]

Done.

+
   // Overridden from Border:
   void Paint(const View& view, gfx::Canvas* canvas) override;
   gfx::Insets GetInsets() const override;
@@ -220,6 +229,8 @@ class VIEWS_EXPORT BubbleBorder : public Border {
   gfx::Size GetSizeForContentsSize(const gfx::Size& contents_size) const;
   gfx::ImageSkia* GetArrowImage() const;
   gfx::Rect GetArrowRect(const gfx::Rect& bounds) const;
+  void GetArrowMaskFromArrowBounds(const gfx::Rect& arrow_bounds,

[tapted, 2016/01/28 05:59:22]

Mask/mask -> Path/path

[karandeepb, 2016/02/04 03:39:27]

Done.

+                                   SkPath* mask) const;
   void DrawArrow(gfx::Canvas* canvas, const gfx::Rect& arrow_bounds) const;
 
   internal::BorderImages* GetImagesForTest() const;