[NTP::Push] Add the classes for sending a breaking news subscription request

components/ntp_snippets/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/ui.gni")
 
 if (is_android) {
   import("//build/config/android/config.gni")
   import("//build/config/android/rules.gni")
 }
 
 static_library("ntp_snippets") {
   sources = [
     "bookmarks/bookmark_last_visit_utils.cc",
     "bookmarks/bookmark_last_visit_utils.h",
     "bookmarks/bookmark_suggestions_provider.cc",
     "bookmarks/bookmark_suggestions_provider.h",
+    "breaking_news/subscription_json_request.cc",
+    "breaking_news/subscription_json_request.h",
+    "breaking_news/subscription_request_params.cc",
+    "breaking_news/subscription_request_params.h",
     "callbacks.h",
     "category.cc",
     "category.h",
     "category_info.cc",
     "category_info.h",
     "category_rankers/category_ranker.h",
     "category_rankers/click_based_category_ranker.cc",
     "category_rankers/click_based_category_ranker.h",
     "category_rankers/constant_category_ranker.cc",
     "category_rankers/constant_category_ranker.h",
@@ skipping 188 matching lines @@
 
   deps = [
     ":ntp_snippets",
     "//base",
     "//components/offline_pages/core",
     "//components/offline_pages/core:test_support",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }