Allow child processes to abort quitting.

base/message_loop.h

Index: base/message_loop.h
diff --git a/base/message_loop.h b/base/message_loop.h
index a64196ce21afd356d2c73ee50c46218a1f9623e8..9822c3c37bec85b16f95b681e9049d0c66e1bafd 100644
--- a/base/message_loop.h
+++ b/base/message_loop.h
@@ -247,6 +247,11 @@ class BASE_API MessageLoop : public base::MessagePump::Delegate {
   // to be processed before returning from Run.
   void QuitNow();
 
+  // Cancels the signal to quit once the pending messages are processed.  This
+  // method may only be called on the same thread that called Run, and Run must
+  // still be on the call stack.
+  void CancelQuit();
+
   // Invokes Quit on the current MessageLoop when run.  Useful to schedule an
   // arbitrary MessageLoop to Quit.
   class QuitTask : public Task {