Post a task to the IO thread to add a ResourceContext in ResourceDispatcherHostImpl.

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 <stddef.h>
 #include <algorithm>
@@ skipping 525 matching lines @@
 void ResourceDispatcherHostImpl::SetDelegate(
     ResourceDispatcherHostDelegate* delegate) {
   delegate_ = delegate;
 }
 
 void ResourceDispatcherHostImpl::SetAllowCrossOriginAuthPrompt(bool value) {
   allow_cross_origin_auth_prompt_ = value;
 }
 
 void ResourceDispatcherHostImpl::AddResourceContext(ResourceContext* context) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);

[mmenke, 2016/01/21 16:33:34]

May want to add a DCHECK to RemoveResourceContext as well, just for
documentation purposes (And out of paranoia)

[Anand Mistry (off Chromium), 2016/01/21 19:41:52]

The reason I didn't is because of the comment about tests destroying the
ResourceContext on the UI thread.

   active_resource_contexts_.insert(context);
 }
 
 void ResourceDispatcherHostImpl::RemoveResourceContext(
     ResourceContext* context) {
   CHECK(ContainsKey(active_resource_contexts_, context));
   active_resource_contexts_.erase(context);
 }
 
 void ResourceDispatcherHostImpl::CancelRequestsForContext(
@@ skipping 1996 matching lines @@
     load_flags |= net::LOAD_PREFETCH;
   }
 
   if (is_sync_load)
     load_flags |= net::LOAD_IGNORE_LIMITS;
 
   return load_flags;
 }
 
 }  // namespace content