cros: Use ScreenManager as a component instead of deriving WizardController from it

chrome/browser/chromeos/login/screens/update_screen_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 "chrome/browser/chromeos/login/screens/update_screen.h"
 
 #include <memory>
 
 #include "base/command_line.h"
 #include "base/macros.h"
@@ skipping 65 matching lines @@
     mock_error_screen_.reset(new MockErrorScreen(
         mock_base_screen_delegate_.get(), mock_network_error_view_.get()));
     EXPECT_CALL(*mock_base_screen_delegate_, ShowCurrentScreen())
         .Times(AnyNumber());
     EXPECT_CALL(*mock_base_screen_delegate_, GetErrorScreen())
         .Times(AnyNumber())
         .WillRepeatedly(Return(mock_error_screen_.get()));
 
     WizardInProcessBrowserTest::SetUpOnMainThread();
 
-    ASSERT_TRUE(WizardController::default_controller() != NULL);
-    update_screen_ = UpdateScreen::Get(WizardController::default_controller());
-    ASSERT_TRUE(update_screen_ != NULL);
+    ASSERT_TRUE(WizardController::default_controller() != nullptr);
+    update_screen_ = UpdateScreen::Get(
+        WizardController::default_controller()->screen_manager());
+    ASSERT_TRUE(update_screen_ != nullptr);
     ASSERT_EQ(WizardController::default_controller()->current_screen(),
               update_screen_);
     update_screen_->base_screen_delegate_ = mock_base_screen_delegate_.get();
   }
 
   void TearDownOnMainThread() override {
     WizardInProcessBrowserTest::TearDownOnMainThread();
     mock_error_screen_.reset();
     mock_network_error_view_.reset();
   }
@@ skipping 310 matching lines @@
       chromeos::UpdateEngineClient::UPDATE_RESULT_FAILED);
   EXPECT_CALL(*mock_base_screen_delegate_,
               OnExit(_, ScreenExitCode::UPDATE_ERROR_CHECKING_FOR_UPDATE, _))
       .Times(1);
 
   update_screen_->OnConnectRequested();
   base::RunLoop().RunUntilIdle();
 }
 
 }  // namespace chromeos