Made a ScopedMockUserManagerEnabler to simplify UserManager mocking life-cycle.

chrome/browser/browser_commands_unittest.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/app/chrome_command_ids.h"
 #include "chrome/browser/bookmarks/bookmark_model.h"
 #include "chrome/browser/ui/browser_list.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/test/base/browser_with_test_window_test.h"
 #include "chrome/test/base/testing_profile.h"
@@ skipping 164 matching lines @@
   ASSERT_EQ(4, browser()->active_index());
   ASSERT_EQ(url2, browser()->GetSelectedWebContents()->GetURL());
 }
 
 // Tests IDC_SEARCH (the Search key on Chrome OS devices).
 #if defined(OS_CHROMEOS)
 
 namespace chromeos {
 
 TEST_F(BrowserCommandsTest, Search) {
-  scoped_ptr<MockUserManager> mock_user_manager(new MockUserManager());
-  UserManager* old_user_manager = UserManager::Set(mock_user_manager.get());
-  EXPECT_CALL(*mock_user_manager, IsLoggedInAsGuest())
+  ScopedMockUserManagerEnabler mock_user_manager;
+  EXPECT_CALL(*mock_user_manager.user_manager(), IsLoggedInAsGuest())
       .Times(1).WillRepeatedly(::testing::Return(false));
 
   // Load a non-NTP URL.
   GURL non_ntp_url("http://foo/");
   AddTab(browser(), non_ntp_url);
   ASSERT_EQ(1, browser()->tab_count());
   EXPECT_EQ(non_ntp_url, browser()->GetSelectedWebContents()->GetURL());
 
   // Pressing the Search key should open a new tab containing the NTP.
   browser()->Search();
   ASSERT_EQ(2, browser()->tab_count());
   ASSERT_EQ(1, browser()->active_index());
   GURL current_url = browser()->GetSelectedWebContents()->GetURL();
   EXPECT_TRUE(current_url.SchemeIs(chrome::kChromeUIScheme));
   EXPECT_EQ(chrome::kChromeUINewTabHost, current_url.host());
 
   // Pressing it a second time while the NTP is open shouldn't change anything.
   browser()->Search();
   ASSERT_EQ(2, browser()->tab_count());
   ASSERT_EQ(1, browser()->active_index());
   current_url = browser()->GetSelectedWebContents()->GetURL();
   EXPECT_TRUE(current_url.SchemeIs(chrome::kChromeUIScheme));
   EXPECT_EQ(chrome::kChromeUINewTabHost, current_url.host());
-
-  UserManager::Set(old_user_manager);
 }
 
 }  // namespace chromeos
 #endif