Support frame tree propagation between renderers in the same browsing instance.

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index 61d98d8faab7f8eaa2baecf2311112c8b073bb36..4d0e484001f91c67f815e4d3ec7e614ea571be6a 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -2746,6 +2746,10 @@ void WebContentsImpl::DidChangeLoadProgress(double progress) {
     delegate_->LoadProgressChanged(this, progress);
 }
 
+void WebContentsImpl::DidUpdateFrameTree(RenderViewHost* rvh) {
+  render_manager_.DidUpdateFrameTree(rvh);
+}
+
 void WebContentsImpl::DocumentAvailableInMainFrame(
     RenderViewHost* render_view_host) {
   FOR_EACH_OBSERVER(WebContentsObserver, observers_,
@@ -2839,6 +2843,15 @@ void WebContentsImpl::RouteMessageEvent(
     return;
 
   ViewMsg_PostMessage_Params new_params(params);
+  RenderViewHost* active_rvh = GetRenderViewHost();
+
+  if (active_rvh->GetProcess()->GetID() != params.target_process_id) {
+    LOG(ERROR) << "Possibly race condition trying to deliver to " <<
+        params.target_process_id << ", which doesn't match " <<
+        active_rvh->GetProcess()->GetID();

[awong, 2012/08/21 19:27:28]

This log isn't going to be seen by anyone. If we need to track this, maybe we
should register a UMA stat (I've never done that before).  Charlie, any
thoughts?

[Charlie Reis, 2012/08/22 22:08:34]

Yeah, I had a similar comment in patch set 10.

+    return;
+  }
+  DCHECK(params.target_frame_id != 0);

[awong, 2012/08/21 19:27:28]

If it is 0, what happens below?

[nasko, 2012/08/21 22:24:13]

0 is an invalid frame ID, so the call won't succeed. We shouldn't be in this
situation though, hence the DCHECK.

 
   // If there is a source_routing_id, translate it to the routing ID for
   // the equivalent swapped out RVH in the target process.  If we need