Position close buttons in bubbles based on a layout delegate constant.

ui/views/views_delegate.cc

Index: ui/views/views_delegate.cc
diff --git a/ui/views/views_delegate.cc b/ui/views/views_delegate.cc
index c6eb9a0132d5cb8d276ca302c9c76405ca023311..c04d5acf76f4d2dfff50ccbc0d78b6a21c26f529 100644
--- a/ui/views/views_delegate.cc
+++ b/ui/views/views_delegate.cc
@@ -152,6 +152,10 @@ gfx::Insets ViewsDelegate::GetButtonPadding() const {
   return gfx::Insets(kButtonExtraTouchSize);
 }
 
+int ViewsDelegate::GetCloseButtonMargin() const {
+  return kCloseButtonMargin;
+}
+
 ViewsDelegate::ViewsDelegate()
     : views_tsc_factory_(new ViewsTouchEditingControllerFactory) {
   DCHECK(!views_delegate);