Allow a Views client to provide a default frameview for window widgets.

ash/shell.cc

Index: ash/shell.cc
===================================================================
--- ash/shell.cc	(revision 117168)
+++ ash/shell.cc	(working copy)
@@ -22,6 +22,7 @@
 #include "ash/wm/compact_status_area_layout_manager.h"
 #include "ash/wm/default_container_event_filter.h"
 #include "ash/wm/default_container_layout_manager.h"
+#include "ash/wm/dialog_frame_view.h"
 #include "ash/wm/modal_container_layout_manager.h"
 #include "ash/wm/power_button_controller.h"
 #include "ash/wm/root_window_event_filter.h"
@@ -394,6 +395,15 @@
   return !modal_container->children().empty();
 }
 
+views::NonClientFrameView* Shell::CreateDefaultNonClientFrameView(
+    views::Widget* widget) {
+  if (CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kAuraGoogleDialogFrames)) {
+    return new internal::DialogFrameView;
+  }
+  return NULL;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Shell, private: