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..92f0ce4317738bdb4f745a35bab4bae6b067a471 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.remote_process_id) {
+    LOG(ERROR) << "Possibly race condition trying to deliver to " <<
+        params.remote_process_id << ", which doesn't match " <<
+        active_rvh->GetProcess()->GetID();
+    return;
+  }
+  DCHECK(params.remote_frame_id != 0);
 
   // 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