update obsolete code.google.com documentation links

components/nacl/loader/nacl_helper_linux.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 COMPONENTS_NACL_LOADER_NACL_HELPER_LINUX_H_
 #define COMPONENTS_NACL_LOADER_NACL_HELPER_LINUX_H_
 
 namespace nacl {
 
 // A mini-zygote specifically for Native Client. This file defines
 // constants used to implement communication between the nacl_helper
 // process and the Chrome zygote.
 
 #define kNaClMaxIPCMessageLength 2048
 
 // Used by Helper to tell Zygote it has started successfully.
 #define kNaClHelperStartupAck "NACLHELPER_OK"
 
 enum NaClZygoteIPCCommand {
   kNaClForkRequest,
   kNaClGetTerminationStatusRequest,
 };
 
 // The next set of constants define global Linux file descriptors.
 // For communications between NaCl loader and browser.
 // See also content/common/zygote_main_linux.cc and
-// http://code.google.com/p/chromium/wiki/LinuxZygote
+// https://chromium.googlesource.com/chromium/src/+/master/docs/linux_zygote.md
 
 // For communications between NaCl loader and zygote.
 #define kNaClZygoteDescriptor 3
 
 } // namespace nacl
 
 #endif  // COMPONENTS_NACL_LOADER_NACL_HELPER_LINUX_H_