Move another block of extension tests to manifest_version 2

chrome/test/data/extensions/api_test/preference/clear/test.html

-<script>
-// Content settings API test
-// Run with browser_tests --gtest_filter=ExtensionApiTest.PreferenceClear
-
-var pw = chrome.experimental.privacy.websites;
-chrome.test.runTests([
-  function getThirdPartyCookiesAllowed() {
-    pw.thirdPartyCookiesAllowed.get({}, chrome.test.callbackPass(
-        function(allowed) {
-          chrome.test.assertEq(
-              allowed,
-              {
-                'value': false,
-                'levelOfControl': "controllable_by_this_extension"
-              },
-              "third-party cookies should be blocked");
-        }));
-  },
-  function setThirdPartyCookiesAllowed() {
-    pw.thirdPartyCookiesAllowed.set(
-        {'value': true},
-        chrome.test.callbackPass());
-  },
-  function clearThirdPartyCookiesAllowed() {
-    pw.thirdPartyCookiesAllowed.clear({}, chrome.test.callbackPass());
-  },
-  function getThirdPartyCookiesAllowed2() {
-    pw.thirdPartyCookiesAllowed.get({}, chrome.test.callbackPass(
-        function(allowed) {
-          chrome.test.assertEq(
-              allowed,
-              {
-                'value': false,
-                'levelOfControl': "controllable_by_this_extension"
-              },
-              "third-party cookies should be blocked");
-        }));
-  }
-]);
-</script>
+<!--
+ * Copyright (c) 2011 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.
+-->
+<script src="test.js"></script>