chromeos: Converts more tests to AshTestBase

ash/system/brightness/tray_brightness_unittest.cc

 // Copyright 2014 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 "ash/system/brightness/tray_brightness.h"
 
 #include <memory>
 
 #include "ash/shell.h"
 #include "ash/system/tray/system_tray_delegate.h"
 #include "ash/system/tray/system_tray_item.h"
-#include "ash/test/ash_test.h"
+#include "ash/test/ash_test_base.h"
 #include "ash/wm/maximize_mode/maximize_mode_controller.h"
 #include "ui/views/view.h"
 
 namespace ash {
 
-class TrayBrightnessTest : public AshTest {
+class TrayBrightnessTest : public test::AshTestBase {
  public:
   TrayBrightnessTest() {}
   ~TrayBrightnessTest() override {}
 
  protected:
   views::View* CreateDefaultView() {
     TrayBrightness tray(NULL);
     // The login status doesn't matter here; supply any random value.
     return tray.CreateDefaultView(LoginStatus::USER);
   }
@@ skipping 62 matching lines @@
   std::unique_ptr<views::View> tray(CreateDetailedView());
   Shell::Get()->maximize_mode_controller()->EnableMaximizeModeWindowManager(
       true);
   EXPECT_TRUE(tray->visible());
   Shell::Get()->maximize_mode_controller()->EnableMaximizeModeWindowManager(
       false);
   EXPECT_TRUE(tray->visible());
 }
 
 }  // namespace ash