Deleting Prefs related pyauto tests which are already being converted to browser_tests.

chrome/test/functional/PYAUTO_TESTS

 # Copyright 2013 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 223 matching lines @@
       # No codesign verification on ChromeOS.
       '-codesign',
       # Sync is already signed in with the login account.
       # So one-click infobar tests do tno apply to chromeos.
       '-infobars.OneClickInfobarTest',
       # Multi-profile doesn't apply to chromeos yet.
       '-multiprofile',
       '-ntp.NTPTest.testDifferentProfileNotAppearInMostVisited',
       # No NaCl support on ChromeOS.
       '-nacl_sdk',
-      # You cannot adjust the downloads directory on ChromeOS.
-      '-prefs.PrefsTest.testDownloadDirPref',
 
       # ==================================================
       # Disabled tests that need to be investigated/fixed.
       # ==================================================
       # crbug.com/132337
       '-autofill.AutofillTest.testTabOrderForEditAddress',
       # crosbug.com/19556
       '-extensions.ExtensionsTest.testAllowAccessFileURLs',
       '-extensions.ExtensionsTest.testAllowIncognitoExtension',
       '-extensions.ExtensionsTest.testDisableEnableExtension',
@@ skipping 319 matching lines @@
       '-search_engines.SearchEnginesTest.testDiscoverSearchEngine',
       '-ntp.NTPTest.testUninstallApp',
       '-ntp.NTPTest.testLaunchAppWithDefaultSettings',
       '-ntp.NTPTest.testLaunchAppRegularTab',
       '-ntp.NTPTest.testLaunchAppPinnedTab',
       '-ntp.NTPTest.testGetAppsWhenInstallApp',
       '-ntp.NTPTest.testLaunchAppNewWindow',
     ],
   },
 }