Navigation transitions: Block first response until after transitions have run.

content/browser/frame_host/render_frame_host_impl.cc

Index: content/browser/frame_host/render_frame_host_impl.cc
diff --git a/content/browser/frame_host/render_frame_host_impl.cc b/content/browser/frame_host/render_frame_host_impl.cc
index a62b7f8cd18f1ac9a9a4f9aa57a18f1fad49ce28..c797be79adaf7cc345ba33b4fc42a8d7d75eb8dd 100644
--- a/content/browser/frame_host/render_frame_host_impl.cc
+++ b/content/browser/frame_host/render_frame_host_impl.cc
@@ -505,6 +505,15 @@ void RenderFrameHostImpl::OnCrossSiteResponse(
       should_replace_current_entry);
 }
 
+void RenderFrameHostImpl::OnDeferredAfterResponseStarted(
+    const GlobalRequestID& global_request_id) {
+  frame_tree_node_->render_manager()->OnDeferredAfterResponseStarted(
+      global_request_id, this);
+
+  if (!GetParent())
+    delegate_->DidDeferAfterResponseStarted();
+}
+
 void RenderFrameHostImpl::SwapOut(RenderFrameProxyHost* proxy) {
   // TODO(creis): Move swapped out state to RFH.  Until then, only update it
   // when swapping out the main frame.