Move Singleton and related structs to namespace base

chrome/browser/ui/app_list/app_list_service_cocoa_mac.mm

 // Copyright 2015 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/app_list/app_list_service_cocoa_mac.h"
 
 #include "base/memory/singleton.h"
 #include "chrome/browser/ui/app_list/app_list_controller_delegate_impl.h"
 #include "chrome/browser/ui/app_list/app_list_view_delegate.h"
 #import "ui/app_list/cocoa/app_list_view_controller.h"
 #import "ui/app_list/cocoa/app_list_window_controller.h"
 
 AppListServiceCocoaMac::~AppListServiceCocoaMac() {
 }
 
 // static
 AppListServiceCocoaMac* AppListServiceCocoaMac::GetInstance() {
-  return Singleton<AppListServiceCocoaMac,
-                   LeakySingletonTraits<AppListServiceCocoaMac>>::get();
+  return base::Singleton<
+      AppListServiceCocoaMac,
+      base::LeakySingletonTraits<AppListServiceCocoaMac>>::get();
 }
 
 void AppListServiceCocoaMac::ShowForProfile(Profile* requested_profile) {
   CreateForProfile(requested_profile);
   DCHECK(ReadyToShow());
   ShowWindowNearDock();
 }
 
 Profile* AppListServiceCocoaMac::GetCurrentAppListProfile() {
   return profile_;
@@ skipping 45 matching lines @@
     // to ensure it will be populated later.
     window_controller_.reset([[AppListWindowController alloc] init]);
   }
   return true;  // Cocoa app list can be shown empty.
 }
 
 AppListServiceCocoaMac::AppListServiceCocoaMac()
     : profile_(nullptr),
       controller_delegate_(new AppListControllerDelegateImpl(this)) {
 }