Convert themes.py to browser test

chrome/test/functional/PYAUTO_TESTS

 # 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.
 #
 # This file lists the pyauto tests that run as a part of the functional test
 # suite.
 #
 # Tests can be enabled on a per-platform basis. Tests not listed here will
 # not be run.
 #
@@ skipping 45 matching lines @@
       'omnibox',
       'passwords',
       'policy_prefs_ui',
       'prefs',
       'prefs_ui',
       'pyauto_webdriver',
       'search_engines',
       'special_tabs',
       'sync.SyncTest',
       'test_pyauto',
-      'themes',
 
       # ==================================================
       # Disabled tests that need to be investigated/fixed.
       # ==================================================
       # crbug.com/123396
       '-fullscreen_mouselock.FullscreenMouselockTest.testPatternsForFSAndML',
       # crbug.com/132665
       '-fullscreen_mouselock.FullscreenMouselockTest.testTabFSExitWhenNavBackToPrevPage',
       '-fullscreen_mouselock.FullscreenMouselockTest.testTabFSExitWhenNavToNewPage',
       '-fullscreen_mouselock.FullscreenMouselockTest.testMLExitWhenNavBackToPrevPage',
@@ skipping 672 matching lines @@
       '-search_engines.SearchEnginesTest.testDiscoverSearchEngine',
       '-ntp.NTPTest.testUninstallApp',
       '-ntp.NTPTest.testLaunchAppWithDefaultSettings',
       '-ntp.NTPTest.testLaunchAppRegularTab',
       '-ntp.NTPTest.testLaunchAppPinnedTab',
       '-ntp.NTPTest.testGetAppsWhenInstallApp',
       '-ntp.NTPTest.testLaunchAppNewWindow',
     ],
   },
 }