Hook up the FocusController behind a flag.

ui/views/corewm/corewm_switches.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/views/corewm/corewm_switches.h"
 
 namespace views {
 namespace corewm {
 namespace switches {
 
+// When set uses the CoreWM FocusController in place of the Ash
+// ActivationController and aura FocusManager.
+const char kUseFocusController[] = "views-corewm-use-focus-controller";
+
 // If present animations are disabled.
 const char kWindowAnimationsDisabled[] =
     "views-corewm-window-animations-disabled";
 
 }  // namespace switches
 }  // namespace corewm
 }  // namespace views