Introduce worker_devtools_agent_route_id for EmbeddedWorker.

content/browser/renderer_host/render_process_host_impl.h

Index: content/browser/renderer_host/render_process_host_impl.h
diff --git a/content/browser/renderer_host/render_process_host_impl.h b/content/browser/renderer_host/render_process_host_impl.h
index 4833f16c672b70dd2bb14a661ab62eb4a70a32cf..20c98f87eff27898e700a42f8a4ed8cc25a4fed9 100644
--- a/content/browser/renderer_host/render_process_host_impl.h
+++ b/content/browser/renderer_host/render_process_host_impl.h
@@ -220,6 +220,11 @@ class CONTENT_EXPORT RenderProcessHostImpl
   static void RegisterRendererMainThreadFactory(
       RendererMainThreadFactoryFunction create);
 
+  // Gets the next available routing id of the proccess. Returns
+  // MSG_ROUTING_NONE if failed. This method needs to be called on IO thread.
+  // If the caller is on UI thread it can directly call GetNextRoutingID.
+  static int GetNextRoutingIDForProcess(int render_process_id);

[jam, 2014/04/29 06:28:22]

i don't see the point of adding this method on RenderProcessHostImpl for two
reasons:
-all the methods are called on the UI threads, so it's better to keep the class
used on one thread only to avoid confusion
-this method doesn't use any internal RPH state, and it's called in one place,
so just move that implementation there

[horo, 2014/04/29 06:54:39]

Done.

+
 #if defined(OS_ANDROID)
   const scoped_refptr<BrowserDemuxerAndroid>& browser_demuxer_android() {
     return browser_demuxer_android_;