Update from https://crrev.com/305340

net/base/host_mapping_rules.cc

 // Copyright (c) 2010 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/base/host_mapping_rules.h"
 
 #include "base/logging.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_tokenizer.h"
 #include "base/strings/string_util.h"
@@ skipping 40 matching lines @@
     // First, we'll check for a match just on hostname.
     // If that fails, we'll check for a match with both hostname and port.
     if (!MatchPattern(host_port->host(), rule.hostname_pattern)) {
       std::string host_port_string = host_port->ToString();
       if (!MatchPattern(host_port_string, rule.hostname_pattern))
         continue;  // This rule doesn't apply.
     }
 
     host_port->set_host(rule.replacement_hostname);
     if (rule.replacement_port != -1)
-      host_port->set_port(rule.replacement_port);
+      host_port->set_port(static_cast<uint16>(rule.replacement_port));
     return true;
   }
 
   return false;
 }
 
 bool HostMappingRules::AddRuleFromString(const std::string& rule_string) {
   std::string trimmed;
   base::TrimWhitespaceASCII(rule_string, base::TRIM_ALL, &trimmed);
   std::vector<std::string> parts;
@@ skipping 29 matching lines @@
   map_rules_.clear();
 
   base::StringTokenizer rules(rules_string, ",");
   while (rules.GetNext()) {
     bool ok = AddRuleFromString(rules.token());
     LOG_IF(ERROR, !ok) << "Failed parsing rule: " << rules.token();
   }
 }
 
 }  // namespace net