Hook up the FocusController behind a flag.

chrome/browser/ui/ash/launcher/shell_window_launcher_controller.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 "chrome/browser/ui/ash/launcher/shell_window_launcher_controller.h"
 
 #include <algorithm>
 
 #include "ash/shell.h"
 #include "ash/wm/window_util.h"
@@ skipping 165 matching lines @@
   // AppLauncherItemController for each |app_launcher_id_|.
   const std::string app_launcher_id_;
 
   DISALLOW_COPY_AND_ASSIGN(AppLauncherItemController);
 };
 
 // ShellWindowLauncherController -----------------------------------------------
 
 ShellWindowLauncherController::ShellWindowLauncherController(
     ChromeLauncherController* owner)
-    : owner_(owner),
+    : ActivationChangeShim(ash::Shell::HasInstance() ?
+          ash::Shell::GetInstance() : NULL),
+      owner_(owner),
       registry_(extensions::ShellWindowRegistry::Get(owner->profile())),
       activation_client_(NULL) {
   registry_->AddObserver(this);
   if (ash::Shell::HasInstance()) {
     if (ash::Shell::GetInstance()->GetPrimaryRootWindow()) {
       activation_client_ = aura::client::GetActivationClient(
           ash::Shell::GetInstance()->GetPrimaryRootWindow());
       if (activation_client_)
         activation_client_->AddObserver(this);
     }
@@ skipping 108 matching lines @@
   WindowToAppLauncherIdMap::iterator iter1 =
       window_to_app_launcher_id_map_.find(window);
   if (iter1 == window_to_app_launcher_id_map_.end())
     return NULL;
   std::string app_launcher_id = iter1->second;
   AppControllerMap::iterator iter2 = app_controller_map_.find(app_launcher_id);
   if (iter2 == app_controller_map_.end())
     return NULL;
   return iter2->second;
 }