Add an experimental permissions API for extensions.

chrome/test/data/extensions/api_test/permissions/experimental_disabled/background.html

 <script>
 // Calls to chrome.experimental.* functions should fail, since this extension
 // has not declared that permission.
 
 chrome.test.runTests([
   function experimental() {
     chrome.tabs.getSelected(null, function(tab) {
       try {
-        chrome.experimental.processes.getProcessForTab(tab.id, 
+        chrome.experimental.processes.getProcessForTab(tab.id,
                                                        function(process) {
           chrome.test.fail();
         });
       } catch (e) {
         chrome.test.succeed();
       }
     });
   }
 ]);
 </script>