[Mac] Enable MacViews bookmark bubble behind --enable-mac-views-dialogs.

components/constrained_window/constrained_window_views.cc

Index: components/constrained_window/constrained_window_views.cc
diff --git a/components/constrained_window/constrained_window_views.cc b/components/constrained_window/constrained_window_views.cc
index d00551385504274b22bd5666e1d1d8496dd99168..8b320dafb277398db50bacae9bd720df42216220 100644
--- a/components/constrained_window/constrained_window_views.cc
+++ b/components/constrained_window/constrained_window_views.cc
@@ -166,6 +166,13 @@ views::Widget* CreateBrowserModalDialogViews(views::DialogDelegate* dialog,
              : nullptr;
   views::Widget* widget =
       views::DialogDelegate::CreateDialogWidget(dialog, NULL, parent_view);
+
+#if defined(OS_MACOSX)
+  // On Mac, window modal dialogs are displayed as sheets, so their position is
+  // managed by the parent window.
+  return widget;

[tapted, 2015/08/21 00:31:52]

I know the compiler allows it.. but there's something weird about making the
code below unreachable on mac. Perhaps

#if defined(OS_MACOSX)
  bool requires_positioning = false;
#else
  bool requires_positioning = dialog->UseNewStyleForThisDialog();
#endif

if (!requires_positioning)
  return widget;



But also this will affect the mac_views_browser build, where the code here
currently works OK (I think..). Is mac_views_browser still OK with this change?
What breaks without it? Maybe there's an alternative..

[jackhou1, 2015/08/21 01:55:58]

Replied in https://codereview.chromium.org/1309583002/

+#endif
+
   if (!dialog->UseNewStyleForThisDialog())
     return widget;
   ModalDialogHost* host = constrained_window_views_client->