Add an opt-out header for HTTP throttling. Never throttle for localhost.

net/base/net_util.h

 // Copyright (c) 2011 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 NET_BASE_NET_UTIL_H_
 #define NET_BASE_NET_UTIL_H_
 #pragma once
 
 #include "build/build_config.h"
 
@@ skipping 409 matching lines @@
 
 // Returns the value of |info's| port (in host byte ordering).
 int GetPortFromAddrinfo(const struct addrinfo* info);
 
 // Same except for struct sockaddr.
 const uint16* GetPortFieldFromSockaddr(const struct sockaddr* address,
                                        socklen_t address_len);
 int GetPortFromSockaddr(const struct sockaddr* address,
                         socklen_t address_len);
 
+// Returns true if |host| is "localhost" or one of the IP-address
+// representations of the loopback address (IPv4 127.0.0.0/8 or IPv6 ::1).
+//
+// Note that this function does not check for IP addresses other than
+// the above being mapped back to the local machine, it only checks
+// for those exact IP addresses.
+bool IsLocalhost(const std::string& host);
+
 // struct that is used by GetNetworkList() to represent a network
 // interface.
 struct NetworkInterface {
   NetworkInterface();
   NetworkInterface(const std::string& name, const IPAddressNumber& address);
   ~NetworkInterface();
 
   std::string name;
   IPAddressNumber address;
 };
 
 typedef std::list<NetworkInterface> NetworkInterfaceList;
 
 // Returns list of network interfaces except loopback interface. If an
 // interface has more than one address, a separate entry is added to
 // the list for each address.
 // Can be called only on a thread that allows IO.
 bool GetNetworkList(NetworkInterfaceList* networks);
 
 }  // namespace net
 
 #endif  // NET_BASE_NET_UTIL_H_