Move EmptyString, kWhitespace and the BOM to base.

ash/shell/launcher_delegate_impl.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 "ash/shell/launcher_delegate_impl.h"
 
 #include "ash/shell.h"
 #include "ash/shell/toplevel_window.h"
 #include "ash/shell/window_watcher.h"
 #include "ash/wm/window_util.h"
@@ skipping 15 matching lines @@
 
 void LauncherDelegateImpl::OnLauncherDestroyed(Launcher* launcher) {
 }
 
 LauncherID LauncherDelegateImpl::GetLauncherIDForAppID(
     const std::string& app_id) {
   return 0;
 }
 
 const std::string& LauncherDelegateImpl::GetAppIDForLauncherID(LauncherID id) {
-  return EmptyString();
+  return base::EmptyString();
 }
 
 void LauncherDelegateImpl::PinAppWithID(const std::string& app_id) {
 }
 
 bool LauncherDelegateImpl::IsAppPinned(const std::string& app_id) {
   return false;
 }
 
 bool LauncherDelegateImpl::CanPin() const {
   return false;
 }
 
 void LauncherDelegateImpl::UnpinAppWithID(const std::string& app_id) {
 }
 
 }  // namespace shell
 }  // namespace ash