Determine routing ID before potentially invalidating the frame

extensions/renderer/messaging_bindings.cc

Index: extensions/renderer/messaging_bindings.cc
diff --git a/extensions/renderer/messaging_bindings.cc b/extensions/renderer/messaging_bindings.cc
index 4a7e733a0737fa9233da10471d130d677ad2462b..a02ad3f512b0471c36043ea85b428e41f81e2d26 100644
--- a/extensions/renderer/messaging_bindings.cc
+++ b/extensions/renderer/messaging_bindings.cc
@@ -449,15 +449,15 @@ void MessagingBindings::DispatchOnConnect(
     const ExtensionMsg_ExternalConnectionInfo& info,
     const std::string& tls_channel_id,
     content::RenderFrame* restrict_to_render_frame) {
+  int routing_id = restrict_to_render_frame
+                       ? restrict_to_render_frame->GetRoutingID()
+                       : MSG_ROUTING_NONE;
   bool port_created = false;
   context_set.ForEach(
       info.target_id, restrict_to_render_frame,
       base::Bind(&DispatchOnConnectToScriptContext, target_port_id,
                  channel_name, &source, info, tls_channel_id, &port_created));

[Devlin, 2016/05/02 13:57:08]

Let's add a comment like
// Note: |restrict_to_render_frame| may be deleted here!
so that we don't (or at least, are less likely to) repeat the same mistake
later.

 
-  int routing_id = restrict_to_render_frame
-                       ? restrict_to_render_frame->GetRoutingID()
-                       : MSG_ROUTING_NONE;
   if (port_created) {
     content::RenderThread::Get()->Send(
         new ExtensionHostMsg_OpenMessagePort(routing_id, target_port_id));