Add Syzygy support to Windows GN build.

chrome/chrome_syzygy.gyp

 # 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.
 {
   'variables': {
     'dest_dir': '<(PRODUCT_DIR)/syzygy',
   },
   'conditions': [
     ['syzyasan==1', {
       'variables': {
@@ skipping 73 matching lines @@
                     'chrome_syzygy.gypi',
                   ],
                 },
               ],
             }],
             # For the official SyzyASan builds just copy chrome_child.dll to the
             # Syzygy directory.
             ['syzyasan==1 and buildtype=="Official"', {
               'targets': [
               {
+                # GN version: //chrome/tools/build/win/syzygy:chrome_child_dll_syzygy_copy
                 'target_name': 'chrome_child_dll_syzygy_copy',
                 'type': 'none',
                 'inputs': [
                   '<(PRODUCT_DIR)/chrome_child.dll',
                   '<(PRODUCT_DIR)/chrome_child.dll.pdb',
                 ],
                 'outputs': [
                   '<(dest_dir)/chrome_child.dll',
                   '<(dest_dir)/chrome_child.dll.pdb',
                 ],
                 'copies': [
                   {
                     'destination': '<(dest_dir)',
                     'files': [
                       '<(PRODUCT_DIR)/chrome_child.dll',
                       '<(PRODUCT_DIR)/chrome_child.dll.pdb',
                     ],
                   },
                 ],
               }],
             }],
           ],
         }],
       ],
     }],
   ],
 }