[url] Reserve space for "scheme://host/" for SchemeHostPort serialization

url/scheme_host_port.cc

 // Copyright 2015 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 "url/scheme_host_port.h"
 
 #include <stdint.h>
 #include <string.h>
 
 #include <tuple>
@@ skipping 184 matching lines @@
 bool SchemeHostPort::operator<(const SchemeHostPort& other) const {
   return std::tie(port_, scheme_, host_) <
          std::tie(other.port_, other.scheme_, other.host_);
 }
 
 std::string SchemeHostPort::SerializeInternal(url::Parsed* parsed) const {
   std::string result;
   if (IsInvalid())
     return result;
 
+  // Reserve enough space for the "normal" case of scheme://host/.
+  result.reserve(scheme_.size() + host_.size() + 4);
+
   if (!scheme_.empty()) {
     parsed->scheme = Component(0, scheme_.length());
     result.append(scheme_);
   }
 
   result.append(kStandardSchemeSeparator);
 
   if (!host_.empty()) {
     parsed->host = Component(result.length(), host_.length());
     result.append(host_);
@@ skipping 12 matching lines @@
     result.push_back(':');
     std::string port(base::UintToString(port_));
     parsed->port = Component(result.length(), port.length());
     result.append(std::move(port));
   }
 
   return result;
 }
 
 }  // namespace url