Add MessageLoop::QuitNow and use it to terminate a sync IPC.

This is a test to observe the performance impact of this change.
As such, I'm reverting r39518 as part of this change.

R=jam
BUG=36310
TEST=none

Review URL: http://codereview.chromium.org/652089

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@39699 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/ipc/ipc_sync_channel.cc b/ipc/ipc_sync_channel.cc
index 3aa7a26f..bb0a245 100644
--- a/ipc/ipc_sync_channel.cc
+++ b/ipc/ipc_sync_channel.cc
@@ -350,7 +350,7 @@
   } else {
     // We got the reply, timed out or the process shutdown.
     DCHECK(event == GetSendDoneEvent());
-    MessageLoop::current()->Quit();
+    MessageLoop::current()->QuitNow();
   }
 }