Add remaining trivial targets for the Linux GN build

content/content.gyp

 # 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': {
     'chromium_code': 1,  # Use higher warning level.
     'chromium_enable_vtune_jit_for_v8%': 0,  # enable the vtune support for V8 engine.
     'directxsdk_exists': '<!pymod_do_main(dir_exists ../third_party/directxsdk)',
   },
@@ skipping 13 matching lines @@
   'conditions': [
     ['OS != "ios"', {
       'includes': [
         '../build/win_precompile.gypi',
         'content_resources.gypi',
       ],
     }],
     ['OS == "win"', {
       'targets': [
         {
+          # GN: //content:content_startup_helper_win
           'target_name': 'content_startup_helper_win',
           'type': 'static_library',
           'include_dirs': [
             '..',
           ],
           'dependencies': [
             '../base/base.gyp:base',
             '../base/base.gyp:base_i18n',
             '../sandbox/sandbox.gyp:sandbox',
           ],
@@ skipping 565 matching lines @@
                   ],
                 },
               ],
             }],
           ],
         },
       ],
     }],  # OS == "android"
   ],
 }