Add help button to app launcher

ash/shell/app_list.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 <string>
 
 #include "ash/shell.h"
 #include "ash/shell/example_factory.h"
 #include "ash/shell/toplevel_window.h"
 #include "ash/shell_delegate.h"
@@ skipping 287 matching lines @@
   }
 
   virtual string16 GetCurrentUserEmail() {
     return string16();
   }
 
   virtual void OpenSettings() {
     // Nothing needs to be done.
   }
 
+  virtual void OpenHelp() {
+    // Nothing needs to be done.
+  }
+
   virtual void OpenFeedback() {
     // Nothing needs to be done.
   }
 
   app_list::AppListModel* model_;
 
   DISALLOW_COPY_AND_ASSIGN(ExampleAppListViewDelegate);
 };
 
 }  // namespace
 
 app_list::AppListViewDelegate* CreateAppListViewDelegate() {
   return new ExampleAppListViewDelegate;
 }
 
 }  // namespace shell
 }  // namespace ash