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 e7fa2be2b1ce36eee7bed1d899863246dc791936..c47604bb8a77bec9cb230036b261bc21da41b973 100644
--- a/ui/views/views_delegate.cc
+++ b/ui/views/views_delegate.cc
@@ -131,6 +131,10 @@ gfx::Insets ViewsDelegate::GetDialogButtonInsets() const {
                      kButtonHEdgeMarginNew);
 }
 
+int ViewsDelegate::GetDialogCloseButtonMargin() const {
+  return kCloseButtonMargin;
+}
+
 int ViewsDelegate::GetDialogRelatedButtonHorizontalSpacing() const {
   return kRelatedButtonHSpacing;
 }