Factoring BuildUserAgent out to a separate lib for GCF can use it.

webkit/glue/webkit_glue.gypi

 # Copyright (c) 2010 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': {
     'conditions': [
       ['inside_chromium_build==0', {
         'webkit_src_dir': '../../../..',
       },{
@@ skipping 87 matching lines @@
           '<(SHARED_INTERMEDIATE_DIR)/webkit',
         ],
       },
       'conditions': [
         ['OS=="win"', {
           'dependencies': ['<(DEPTH)/build/win/system.gyp:cygwin'],
         }],
       ],
     },
     {
+      'target_name': 'webkit_user_agent',
+      'type': '<(library)',
+      'msvs_guid': 'DB162DE1-7D56-4C4A-8A9F-80D396CD7AA8',
+      'dependencies': [
+        '<(DEPTH)/app/app.gyp:app_base',
+        '<(DEPTH)/base/base.gyp:base_i18n',
+      ],
+      'actions': [
+        {
+          'action_name': 'webkit_version',
+          'inputs': [
+            '../build/webkit_version.py',
+            '<(webkit_src_dir)/WebCore/Configurations/Version.xcconfig',
+          ],
+          'outputs': [
+            '<(INTERMEDIATE_DIR)/webkit_version.h',
+          ],
+          'action': ['python', '<@(_inputs)', '<(INTERMEDIATE_DIR)'],
+        },
+      ],
+      'include_dirs': [
+        '<(INTERMEDIATE_DIR)',
+      ],
+      'sources': [
+        'user_agent.cc',
+        'user_agent.h',
+      ],
+      'conditions': [
+      ],
+    },
+    {
       'target_name': 'glue',
       'type': '<(library)',
       'msvs_guid': 'C66B126D-0ECE-4CA2-B6DC-FA780AFBBF09',
       'dependencies': [
         '<(DEPTH)/app/app.gyp:app_base',
         '<(DEPTH)/base/base.gyp:base_i18n',
         '<(DEPTH)/gpu/gpu.gyp:gles2_implementation',
         '<(DEPTH)/net/net.gyp:net',
         '<(DEPTH)/printing/printing.gyp:printing',
         '<(DEPTH)/skia/skia.gyp:skia',
         '<(DEPTH)/third_party/icu/icu.gyp:icui18n',
         '<(DEPTH)/third_party/icu/icu.gyp:icuuc',
         '<(DEPTH)/third_party/npapi/npapi.gyp:npapi',
         '<(DEPTH)/third_party/ppapi/ppapi.gyp:ppapi_c',
         'webkit_resources',
         'webkit_strings',
+        'webkit_user_agent',
       ],
       'actions': [
-        {
-          'action_name': 'webkit_version',
-          'inputs': [
-            '../build/webkit_version.py',
-            '<(webkit_src_dir)/WebCore/Configurations/Version.xcconfig',
-          ],
-          'outputs': [
-            '<(INTERMEDIATE_DIR)/webkit_version.h',
-          ],
-          'action': ['python', '<@(_inputs)', '<(INTERMEDIATE_DIR)'],
-        },
       ],
       'include_dirs': [
         '<(INTERMEDIATE_DIR)',
         '<(SHARED_INTERMEDIATE_DIR)/webkit',
       ],
       'sources': [
         # This list contains all .h, .cc, and .mm files in glue except for
         # those in the test subdirectory and those with unittest in in their
         # names.
         'media/buffered_data_source.cc',
@@ skipping 278 matching lines @@
         }],
         ['inside_chromium_build==0', {
           'dependencies': [
             '<(DEPTH)/webkit/support/setup_third_party.gyp:third_party_headers',
           ],
         }],
       ],
     },
   ],
 }