[Extensions] Begin making Extension port initialization asynchronous

chrome/browser/renderer_host/chrome_extension_message_filter.cc

Index: chrome/browser/renderer_host/chrome_extension_message_filter.cc
diff --git a/chrome/browser/renderer_host/chrome_extension_message_filter.cc b/chrome/browser/renderer_host/chrome_extension_message_filter.cc
index a34a8ac157eb10b35ce6136272eb67af6f47071c..1533889e36885c2947d0d464e816d1d08e135233 100644
--- a/chrome/browser/renderer_host/chrome_extension_message_filter.cc
+++ b/chrome/browser/renderer_host/chrome_extension_message_filter.cc
@@ -129,9 +129,11 @@ void ChromeExtensionMessageFilter::OnOpenChannelToExtension(
     const ExtensionMsg_ExternalConnectionInfo& info,
     const std::string& channel_name,
     bool include_tls_channel_id,
-    int* port_id) {
-  int port2_id;
-  extensions::MessageService::AllocatePortIdPair(port_id, &port2_id);
+    int request_id) {
+  int port1_id = 0;
+  int port2_id = 0;
+  extensions::MessageService::AllocatePortIdPair(&port1_id, &port2_id);
+  Send(new ExtensionMsg_AssignPortId(routing_id, port1_id, request_id));
 
   BrowserThread::PostTask(
       BrowserThread::UI, FROM_HERE,