Eliminate a potential race in IPC::ChannelProxy

ipc/ipc_channel_proxy.cc

Index: ipc/ipc_channel_proxy.cc
diff --git a/ipc/ipc_channel_proxy.cc b/ipc/ipc_channel_proxy.cc
index 50431d575604c43045d174fa0800613bba17d463..de9f0230a03c875057e256a2f90098c45219629a 100644
--- a/ipc/ipc_channel_proxy.cc
+++ b/ipc/ipc_channel_proxy.cc
@@ -143,7 +143,8 @@ ChannelProxy::Context::Context(Listener* listener,
       ipc_task_runner_(ipc_task_runner),
       channel_connected_called_(false),
       message_filter_router_(new MessageFilterRouter()),
-      peer_pid_(base::kNullProcessId) {
+      peer_pid_(base::kNullProcessId),
+      channel_is_connected_(false) {
   DCHECK(ipc_task_runner_.get());
 }
 
@@ -200,6 +201,7 @@ void ChannelProxy::Context::OnChannelConnected(int32 peer_pid) {
   // creates a ChannelProxy, calls AddFilter, and then right after starts the
   // peer process.  The IO thread could receive a message before the task to add
   // the filter is run on the IO thread.
+  channel_is_connected_ = true;
   OnAddFilter();
 
   // We cache off the peer_pid so it can be safely accessed from both threads.
@@ -278,6 +280,9 @@ void ChannelProxy::Context::OnSendMessage(scoped_ptr<Message> message) {
 
 // Called on the IPC::Channel thread
 void ChannelProxy::Context::OnAddFilter() {
+  if (!channel_is_connected_)
+    return;
+
   std::vector<scoped_refptr<MessageFilter> > new_filters;
   {
     base::AutoLock auto_lock(pending_filters_lock_);