Cleanup: Remove more unneeded browser_thread.h includes.

chrome/browser/chromeos/login/user_manager.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/chromeos/login/user_manager.h"
 
 #include "chrome/browser/chromeos/login/user_manager_impl.h"
-#include "content/public/browser/browser_thread.h"
 
 namespace chromeos {
 
 // static
 const char UserManager::kStubUser[] = "stub-user@example.com";
 
 // Class that is holds pointer to UserManager instance.
 // One could set UserManager mock instance through it (see UserManager::Set).
 class UserManagerImplWrapper {
  public:
@@ skipping 41 matching lines @@
 UserManager* UserManager::Set(UserManager* mock) {
   UserManager* old_manager = UserManagerImplWrapper::GetInstance()->release();
   UserManagerImplWrapper::GetInstance()->reset(mock);
   return old_manager;
 }
 
 UserManager::~UserManager() {
 }
 
 }  // namespace chromeos