Update from https://crrev.com/306655

net/dns/dns_transaction.cc

Index: net/dns/dns_transaction.cc
diff --git a/net/dns/dns_transaction.cc b/net/dns/dns_transaction.cc
index 03eb7f26947887fdcb50a5cc9dc3c85968bd8b94..beb2197dd55b7bc50d39c71cb70d46c29bfd2a77 100644
--- a/net/dns/dns_transaction.cc
+++ b/net/dns/dns_transaction.cc
@@ -392,8 +392,10 @@ class DnsTCPAttempt : public DnsAttempt {
     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;