IPC: Fix attachment brokering race condition.

content/child/child_thread_impl.cc

Index: content/child/child_thread_impl.cc
diff --git a/content/child/child_thread_impl.cc b/content/child/child_thread_impl.cc
index bdccbdad8141371ab04e725110d3b391a438a7f2..733d538df65e3a19f5b6c28b72c5e5b890e38c41 100644
--- a/content/child/child_thread_impl.cc
+++ b/content/child/child_thread_impl.cc
@@ -458,12 +458,12 @@ void ChildThreadImpl::Init(const Options& options) {
     channel_->AddFilter(startup_filter);
   }
 
-  ConnectChannel(
-      options.use_mojo_channel,
-      mojo::MakeScopedHandle(options.in_process_message_pipe_handle));
   IPC::AttachmentBroker* broker = IPC::AttachmentBroker::GetGlobal();
   if (broker && !broker->IsPrivilegedBroker())
     broker->RegisterBrokerCommunicationChannel(channel_.get());
+  ConnectChannel(
+      options.use_mojo_channel,
+      mojo::MakeScopedHandle(options.in_process_message_pipe_handle));
 
   int connection_timeout = kConnectionTimeoutS;
   std::string connection_override =