MacViews: fix bubble direction in RTL.

ui/views/style/platform_style.h

Index: ui/views/style/platform_style.h
diff --git a/ui/views/style/platform_style.h b/ui/views/style/platform_style.h
index 67c7ae0fcd69d7c8ccdc6c812f199d99e9d94f9f..181c18076f179045bf1f13b9b2aad9a5ffdb19ab 100644
--- a/ui/views/style/platform_style.h
+++ b/ui/views/style/platform_style.h
@@ -57,6 +57,10 @@ class VIEWS_EXPORT PlatformStyle {
   // Whether ripples should be used for visual feedback on control activation.
   static const bool kUseRipples;
 
+  // Whether to mirror the arrow of bubble dialogs in RTL, such that the bubble
+  // opens in the opposite direction.
+  static const bool kMirrorBubbleArrowInRTLByDefault;
+
   // Creates an ImageSkia containing the image to use for the combobox arrow.
   // The |is_enabled| argument is true if the control the arrow is for is
   // enabled, and false if the control is disabled. The |style| argument is the