Update from https://crrev.com/306655

net/dns/dns_transaction.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 "net/dns/dns_transaction.h"
 
 #include <deque>
 #include <string>
 #include <vector>
 
@@ skipping 374 matching lines @@
                     base::TimeTicks::Now() - start_time_);
     }
     return rv;
   }
 
   int DoConnectComplete(int rv) {
     DCHECK_NE(ERR_IO_PENDING, rv);
     if (rv < 0)
       return rv;
 
-    base::WriteBigEndian<uint16>(length_buffer_->data(),
-                                 query_->io_buffer()->size());
+    uint16 query_size = static_cast<uint16>(query_->io_buffer()->size());
+    if (static_cast<int>(query_size) != query_->io_buffer()->size())
+      return ERR_FAILED;
+    base::WriteBigEndian<uint16>(length_buffer_->data(), query_size);
     buffer_ =
         new DrainableIOBuffer(length_buffer_.get(), length_buffer_->size());
     next_state_ = STATE_SEND_LENGTH;
     return OK;
   }
 
   int DoSendLength(int rv) {
     DCHECK_NE(ERR_IO_PENDING, rv);
     if (rv < 0)
       return rv;
@@ skipping 573 matching lines @@
 }  // namespace
 
 // static
 scoped_ptr<DnsTransactionFactory> DnsTransactionFactory::CreateFactory(
     DnsSession* session) {
   return scoped_ptr<DnsTransactionFactory>(
       new DnsTransactionFactoryImpl(session));
 }
 
 }  // namespace net