Replace "nested message loop" with "nested run loop" in comments.

content/public/test/test_download_request_handler.h

Index: content/public/test/test_download_request_handler.h
diff --git a/content/public/test/test_download_request_handler.h b/content/public/test/test_download_request_handler.h
index 629d8d6172b0e906d97785f9c33ce5f22548417b..2fa1a0dea25d64e6d40f3a899ec8b532d701fb90 100644
--- a/content/public/test/test_download_request_handler.h
+++ b/content/public/test/test_download_request_handler.h
@@ -237,7 +237,7 @@ class TestDownloadRequestHandler : public base::NonThreadSafe {
   //   different runs of the same test.
   //
   // * Initialization of the handler synchronously runs a task on the
-  //   BrowserThread::IO thread using a nested message loop. Only construct an
+  //   BrowserThread::IO thread using a nested run loop. Only construct an
   //   instance of this object after browser threads have been initialized.
   TestDownloadRequestHandler();