Speed up custom wallpaper switching time and wallpaper manager code refactor

chrome/browser/chromeos/login/existing_user_controller_browsertest.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 "base/bind.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "chrome/browser/chromeos/cros/cros_in_process_browser_test.h"
 #include "chrome/browser/chromeos/cros/cros_mock.h"
@@ skipping 118 matching lines @@
     LoginUtils::Set(mock_login_utils_);
     EXPECT_CALL(*mock_login_utils_, PrewarmAuthentication())
         .Times(AnyNumber());
     EXPECT_CALL(*mock_login_utils_, StopBackgroundFetchers())
         .Times(AnyNumber());
     EXPECT_CALL(*mock_login_utils_, DelegateDeleted(_))
         .Times(1);
 
     mock_login_display_host_.reset(new MockLoginDisplayHost());
 
-    EXPECT_CALL(*mock_user_manager_.user_manager(), InitializeWallpaper())
-        .Times(1);
     EXPECT_CALL(*mock_user_manager_.user_manager(), IsKnownUser(kUsername))
         .Times(AnyNumber())
         .WillRepeatedly(Return(true));
     EXPECT_CALL(*mock_user_manager_.user_manager(), IsKnownUser(kNewUsername))
         .Times(AnyNumber())
         .WillRepeatedly(Return(false));
     EXPECT_CALL(*mock_user_manager_.user_manager(), IsUserLoggedIn())
         .Times(AnyNumber())
         .WillRepeatedly(Return(false));
     EXPECT_CALL(*mock_user_manager_.user_manager(), IsLoggedInAsGuest())
@@ skipping 166 matching lines @@
   EXPECT_CALL(*mock_login_display_host_.get(), OnCompleteLogin())
       .Times(1);
   EXPECT_CALL(*mock_user_manager_.user_manager(), IsCurrentUserNew())
       .Times(AnyNumber())
       .WillRepeatedly(Return(true));
   existing_user_controller()->CompleteLogin(kNewUsername, kPassword);
   ui_test_utils::RunAllPendingInMessageLoop();
 }
 
 }  // namespace chromeos