Allow child processes to abort quitting.

content/common/child_thread.h

Index: content/common/child_thread.h
diff --git a/content/common/child_thread.h b/content/common/child_thread.h
index f2ac864ade86381c86d90f91d72c22abd6852ad3..27c05c49ea86f6ec4c27a8bb2746f2a4c877d64e 100644
--- a/content/common/child_thread.h
+++ b/content/common/child_thread.h
@@ -76,6 +76,9 @@ class ChildThread : public IPC::Channel::Listener,
   // Called when the process refcount is 0.
   void OnProcessFinalRelease();
 
+  // Called if the process refcount comes back from 0 before exiting.
+  void AbortProcessShutdown();
+
   virtual bool OnControlMessageReceived(const IPC::Message& msg);
   virtual void OnAskBeforeShutdown();
   virtual void OnShutdown();
@@ -117,6 +120,10 @@ class ChildThread : public IPC::Channel::Listener,
   // that would addref it.
   bool check_with_browser_before_shutdown_;
 
+  // If we need to check with the browser before shutdown, this keeps track of
+  // whether we still intend to shutdown by the time we hear the response.
+  bool is_waiting_to_shutdown_;
+
   // The OnChannelError() callback was invoked - the channel is dead, don't
   // attempt to communicate.
   bool on_channel_error_called_;