Move contentSettings extension API out of experimental

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

 <script>
 // Content settings API test
 // Run with browser_tests --gtest_filter=ExtensionApiTest.ContentSettings
 
-var cs = chrome.experimental.contentSettings;
+var cs = chrome.contentSettings;
 var default_content_settings = {
   "cookies": "session_only",
   "images": "allow",
   "javascript": "block",
   "plugins": "allow",
   "popups": "block",
   // TODO(bauerb)
   // "geolocation": "ask",
   "notifications": "ask"
 };
@@ skipping 67 matching lines @@
       'setting': 'block'
     }, chrome.test.callbackFail("Specific paths are not allowed."));
     cs.javascript.set({
       'primaryPattern': 'http://example.com/*',
       'secondaryPattern': 'file:///home/hansmoleman/*',
       'setting': 'allow'
     }, chrome.test.callbackFail("Path wildcards in file URL patterns are not allowed."));
   }
 ]);
 </script>