Cleanup return values in chrome/browser/net

chrome/browser/net/firefox_proxy_settings.h

 // Copyright 2013 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.
 
 #ifndef CHROME_BROWSER_NET_FIREFOX_PROXY_SETTINGS_H_
 #define CHROME_BROWSER_NET_FIREFOX_PROXY_SETTINGS_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 50 matching lines @@
   int gopher_proxy_port() const { return gopher_proxy_port_; }
 
   std::string socks_host() const { return socks_host_; }
   int socks_port() const { return socks_port_; }
   SOCKSVersion socks_version() const { return socks_version_; }
 
   std::vector<std::string> proxy_bypass_list() const {
     return proxy_bypass_list_;
   }
 
-  const std::string autoconfig_url() const {
-    return autoconfig_url_;
-  }
+  const std::string& autoconfig_url() const { return autoconfig_url_; }
 
   // Converts a FirefoxProxySettings object to a net::ProxyConfig.
   // On success returns true and fills |config| with the result.
   bool ToProxyConfig(net::ProxyConfig* config);
 
  protected:
   // Gets the settings from the passed prefs.js file and returns true if
   // successful.
   // Protected for tests.
   static bool GetSettingsFromFile(const base::FilePath& pref_file,
@@ skipping 19 matching lines @@
   SOCKSVersion socks_version_;
 
   std::vector<std::string> proxy_bypass_list_;
 
   std::string autoconfig_url_;
 
   DISALLOW_COPY_AND_ASSIGN(FirefoxProxySettings);
 };
 
 #endif  // CHROME_BROWSER_NET_FIREFOX_PROXY_SETTINGS_H_