Don't swap out the old RenderFrameHost until the new one commits.

content/browser/loader/resource_dispatcher_host_impl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // See http://dev.chromium.org/developers/design-documents/multi-process-resource-loading
 
 #include "content/browser/loader/resource_dispatcher_host_impl.h"
 
 #include <algorithm>
 #include <set>
@@ skipping 1389 matching lines @@
 void ResourceDispatcherHostImpl::CancelTransferringNavigation(
     const GlobalRequestID& id) {
   // Request should still exist and be in the middle of a transfer.
   DCHECK(IsTransferredNavigation(id));
   RemovePendingRequest(id.child_id, id.request_id);
 }
 
 void ResourceDispatcherHostImpl::ResumeDeferredNavigation(
     const GlobalRequestID& id) {
   ResourceLoader* loader = GetLoader(id);
-  if (loader) {
-    // The response we were meant to resume could have already been canceled.
-    ResourceRequestInfoImpl* info = loader->GetRequestInfo();
-    if (info->cross_site_handler())
-      info->cross_site_handler()->ResumeResponse();
-  }
+  // The response we were meant to resume could have already been canceled.
+  if (loader)
+    loader->CompleteTransfer();

[Charlie Reis, 2014/08/18 23:27:53]

Note: We now only use this for transfers that end up not needing a new process. 
This means we can "complete" the transfer without changing any of the request's
metadata.

[nasko, 2014/08/19 16:45:23]

Converting to this doesn't remove the cross_site_handler() on the
ResourceRequestInfo object. Is this ok?
Also, if we complete here, does that work fine for the transition navigations?
They rely on the cross-site resource handler to pause the navigation through a
defer/resume.

[Charlie Reis, 2014/08/19 21:20:31]

I think the sole difference is that we set loader->is_transferring_ to false
before calling cross_site_handler()->ResumeResponse().  That should still remove
it from the info object.
I *think* their pause and resume logic should continue to work, since they have
a similar set of operations as transfers.  I admit that I don't have full
knowledge of what they're relying on CSRH for, but I didn't see any test
failures from the change.

 }
 
 // The object died, so cancel and detach all requests associated with it except
 // for downloads and detachable resources, which belong to the browser process
 // even if initiated via a renderer.
 void ResourceDispatcherHostImpl::CancelRequestsForProcess(int child_id) {
   CancelRequestsForRoute(child_id, -1 /* cancel all */);
   registered_temp_files_.erase(child_id);
 }
 
@@ skipping 571 matching lines @@
 
   // Add a flag to selectively bypass the data reduction proxy if the resource
   // type is not an image.
   if (request_data.resource_type != RESOURCE_TYPE_IMAGE)
     load_flags |= net::LOAD_BYPASS_DATA_REDUCTION_PROXY;
 
   return load_flags;
 }
 
 }  // namespace content