Remove direct usage of BrowserThreadImpl in tests

net/url_request/test_url_fetcher_factory.h

Index: net/url_request/test_url_fetcher_factory.h
diff --git a/net/url_request/test_url_fetcher_factory.h b/net/url_request/test_url_fetcher_factory.h
index e1c9e9b6856c636653a35de6d597a9180eb19479..00d140357a6ed1d384fb2902d0d5bfe7f3f3d7fd 100644
--- a/net/url_request/test_url_fetcher_factory.h
+++ b/net/url_request/test_url_fetcher_factory.h
@@ -45,10 +45,9 @@ class ScopedURLFetcherFactory : public base::NonThreadSafe {
 // the callback method when appropriate. In this way it's easy to mock a
 // URLFetcher.
 // Typical usage:
-//   // TestURLFetcher requires a MessageLoop.
-//   MessageLoop message_loop;
-//   // And an IO thread to release URLRequestContextGetter in URLFetcher::Core.
-//   BrowserThreadImpl io_thread(BrowserThread::IO, &message_loop);
+//   // TestURLFetcher requires a MessageLoop and an IO thread to release
+//   // URLRequestContextGetter in URLFetcher::Core.
+//   TestBrowserThreadBundle thread_bundle_;
 //   // Create factory (it automatically sets itself as URLFetcher's factory).
 //   TestURLFetcherFactory factory;
 //   // Do something that triggers creation of a URLFetcher.