Made all enums of preferences api unix_hacker_style

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

 <script>
 // Content settings API test
 // Run with browser_tests --gtest_filter=ExtensionApiTest.ContentSettingsClear
 
 var cs = chrome.experimental.contentSettings;
 chrome.test.runTests([
   function getBlockThirdPartyCookies() {
     cs.misc.blockThirdPartyCookies.get({}, chrome.test.callbackPass(
         function(block) {
           chrome.test.assertEq(
               block,
               {
                 'value': true,
-                'levelOfControl': "ControllableByThisExtension"
+                'levelOfControl': "controllable_by_this_extension"
               },
               "third-party cookies should be blocked");
         }));
   },
   function setBlockThirdPartyCookies() {
     cs.misc.blockThirdPartyCookies.set(
         {'value': false},
         chrome.test.callbackPass());
   },
   function clearBlockThirdPartyCookies() {
     cs.misc.blockThirdPartyCookies.clear({}, chrome.test.callbackPass());
   },
   function getBlockThirdPartyCookies2() {
     cs.misc.blockThirdPartyCookies.get({}, chrome.test.callbackPass(
         function(block) {
           chrome.test.assertEq(
               block,
               {
                 'value': true,
-                'levelOfControl': "ControllableByThisExtension"
+                'levelOfControl': "controllable_by_this_extension"
               },
               "third-party cookies should be blocked");
         }));
   }
 ]);
 </script>