Add frameId to MessageSender (extension messaging API)

extensions/renderer/runtime_custom_bindings.cc

Index: extensions/renderer/runtime_custom_bindings.cc
diff --git a/extensions/renderer/runtime_custom_bindings.cc b/extensions/renderer/runtime_custom_bindings.cc
index fb6851e0f5392a82a0c02963478ccd1a79703480..159adca031a4825c888e50911103406fce7d9d28 100644
--- a/extensions/renderer/runtime_custom_bindings.cc
+++ b/extensions/renderer/runtime_custom_bindings.cc
@@ -58,6 +58,11 @@ void RuntimeCustomBindings::OpenChannelToExtension(
 
   ExtensionMsg_ExternalConnectionInfo info;
 
+  if (blink::WebFrame* webframe = context()->web_frame())
+    info.source_frame_id = !webframe->parent() ? 0 : renderview->GetRoutingID();
+  else
+    info.source_frame_id = -1;

[not at google - send to devlin, 2014/11/10 18:36:42]

You should be able to determine this on the browser, by pulling out the
RenderFrameHosts's routing ID or whatever.

[robwu, 2014/11/10 21:43:07]

I need to know whether the request originated from the main frame. This
information is readily available here, so I figured that putting the frameId
assignment here would be best.

[not at google - send to devlin, 2014/11/10 22:20:17]

I'm not totally sure what you mean here, but the browser can be trusted, the
renderer cannot. The browser knows about frame IDs, so that's where they should
originate.

[robwu, 2014/11/10 23:13:38]

Updated CL. I've added a new IPC message ExtensionMsg_TabConnectionInfo because
ExtensionMsg_DispatchOnConnect had already reached the maximum of 5 arguments,
and because source_tab and source_frame_id are strongly relayed.

+
   // For messaging APIs, hosted apps should be considered a web page so hide
   // its extension ID.
   const Extension* extension = context()->extension();