File manager: use pre-bound "self" variable instead of "this".

The onError function is called as a free function hence has no associated "this" object.

BUG=141809

Review URL: https://chromiumcodereview.appspot.com/10826241

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@151199 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/resources/file_manager/js/file_copy_manager.js

@@ -680,7 +680,7 @@ FileCopyManager.prototype.serviceNextTaskEntry_ = function(
   }
 
   function onError(reason, data) {
-    this.log_('serviceNextTaskEntry error: ' + reason + ':', data);
+    self.log_('serviceNextTaskEntry error: ' + reason + ':', data);
     errorCallback(new FileCopyManager.Error(reason, data));
   }