Process incoming IQs in the same order that they were sent.

remoting/signaling/iq_sender.cc

 // Copyright 2014 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.
 
 #include "remoting/signaling/iq_sender.h"
 
 #include <memory>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 30 matching lines @@
 }
 
 IqSender::~IqSender() {
   signal_strategy_->RemoveListener(this);
 }
 
 std::unique_ptr<IqRequest> IqSender::SendIq(
     std::unique_ptr<buzz::XmlElement> stanza,
     const ReplyCallback& callback) {
   std::string addressee = stanza->Attr(buzz::QN_TO);
-  std::string id = signal_strategy_->GetNextId();
-  stanza->AddAttr(buzz::QN_ID, id);
+  std::string id = stanza->Attr(buzz::QN_ID);
+  if (id.empty()) {
+    id = signal_strategy_->GetNextId();
+    stanza->AddAttr(buzz::QN_ID, id);
+  }
   if (!signal_strategy_->SendStanza(std::move(stanza))) {
     return nullptr;
   }
   DCHECK(requests_.find(id) == requests_.end());
   std::unique_ptr<IqRequest> request(new IqRequest(this, callback, addressee));
   if (!callback.is_null())
     requests_[id] = request.get();
   return request;
 }
 
@@ skipping 96 matching lines @@
   base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE, base::Bind(&IqRequest::DeliverResponse, AsWeakPtr(),
                             base::Passed(&stanza_copy)));
 }
 
 void IqRequest::DeliverResponse(std::unique_ptr<buzz::XmlElement> stanza) {
   CallCallback(stanza.get());
 }
 
 }  // namespace remoting