[Chromoting] Drop unordered messages instead of crashing

remoting/protocol/jingle_session.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.
 
 #include "remoting/protocol/jingle_session.h"
 
 #include <stdint.h>
 
 #include <limits>
 #include <memory>
@@ skipping 125 matching lines @@
   if (current == kInvalid) {
     result.push_back(std::move(message));
     return result;
   }
 
   if (next_incoming_ == kAny) {
     next_incoming_ = current;
   }
 
   // Ensure there are no duplicate sequence ids.
-  DCHECK_GE(current, next_incoming_);
-  DCHECK(queue_.find(current) == queue_.end());
-
-  queue_.insert(std::make_pair(current, std::move(message)));
+  if (current < next_incoming_) {
+    LOG(WARNING) << "An unordered message will be dropped, expected= "
+                 << next_incoming_ << " current= " << current;
+  } else {
+    DCHECK(queue_.find(current) == queue_.end());
+    queue_.insert(std::make_pair(current, std::move(message)));
+  }
 
   auto it = queue_.begin();
   while (it != queue_.end() && it->first == next_incoming_) {
     result.push_back(std::move(it->second));
     it = queue_.erase(it);
     next_incoming_++;
   }
 
   if (current - next_incoming_ >= 3) {
     LOG(WARNING) << "Multiple messages are missing: expected= "
@@ skipping 640 matching lines @@
       authenticator_->GetNextMessage()));
   SendMessage(std::move(message));
 }
 
 std::string JingleSession::GetNextOutgoingId() {
   return outgoing_id_prefix_ + "_" + base::IntToString(++next_outgoing_id_);
 }
 
 }  // namespace protocol
 }  // namespace remoting