Append variation headers when fetching snippets.

components/ntp_snippets.gypi

 # Copyright 2015 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.
 
 {
   'targets': [
     {
       # GN version: //components/ntp_snippets
       'target_name': 'ntp_snippets',
       'type': 'static_library',
       'include_dirs': [
         '..',
       ],
       'dependencies': [
         '../base/base.gyp:base',
         '../google_apis/google_apis.gyp:google_apis',
         '../net/net.gyp:net',
         '../url/url.gyp:url_lib',
         '../third_party/icu/icu.gyp:icuuc',
         'data_use_measurement_core',
         'image_fetcher',
         'keyed_service_core',
         'leveldb_proto',
         'prefs/prefs.gyp:prefs',
         'signin_core_browser',
         'suggestions',
         'sync_driver',
         'variations',
+        'variations_net',
       ],
       'sources': [
         'ntp_snippets/content_suggestion.cc',
         'ntp_snippets/content_suggestion.h',
         'ntp_snippets/content_suggestions_category_status.cc',
         'ntp_snippets/content_suggestions_category_status.h',
         'ntp_snippets/content_suggestions_category.h',
         'ntp_snippets/content_suggestions_provider.cc',
         'ntp_snippets/content_suggestions_provider.h',
         'ntp_snippets/content_suggestions_service.cc',
@@ skipping 18 matching lines @@
         'ntp_snippets/switches.h',
       ],
       'variables': {
         'proto_in_dir': 'ntp_snippets/proto',
         'proto_out_dir': 'components/ntp_snippets/proto',
       },
       'includes': [ '../build/protoc.gypi' ],
     },
   ],
 }