content: Port layout_test_helper target to GN build.

content/content_shell.gypi

 # Copyright (c) 2012 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': {
     'content_shell_product_name': 'Content Shell',
     # The "19" is so that sites that sniff for version think that this is
     # something reasonably current; the "77.34.5" is a hint that this isn't a
     # standard Chrome.
@@ skipping 779 matching lines @@
             'files': ['<(PRODUCT_DIR)/libtest_netscape_plugin.so'],
           }],
         }],
       ],
     }
   ],
   'conditions': [
     ['OS=="mac" or OS=="win"', {
       'targets': [
         {
+          # GN version: //content/shell:layout_test_helper
           'target_name': 'layout_test_helper',
           'type': 'executable',
           'sources': [
             'shell/renderer/test_runner/helper/layout_test_helper_mac.mm',
             'shell/renderer/test_runner/helper/layout_test_helper_win.cc',
           ],
           'conditions': [
             ['OS=="mac"', {
               'link_settings': {
                 'libraries': [
@@ skipping 356 matching lines @@
                 '--input_symbol', '<(PRODUCT_DIR)/content_shell.exe.pdb',
                 '--destination_dir', '<(dest_dir)',
               ],
             },
           ],
         },
       ],
     }],  # OS=="win" and fastbuild==0 and target_arch=="ia32"
   ]
 }