[User classifier] Add a unit-test

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")
 }
@@ skipping 134 matching lines @@
     "remote/remote_suggestions_database_unittest.cc",
     "remote/remote_suggestions_fetcher_unittest.cc",
     "remote/remote_suggestions_provider_impl_unittest.cc",
     "remote/remote_suggestions_status_service_unittest.cc",
     "remote/request_throttler_unittest.cc",
     "remote/scheduling_remote_suggestions_provider_unittest.cc",
     "remote/test_utils.cc",
     "remote/test_utils.h",
     "sessions/foreign_sessions_suggestions_provider_unittest.cc",
     "sessions/tab_delegate_sync_adapter_unittest.cc",
+    "user_classifier_unittest.cc",
   ]
 
   deps = [
     ":ntp_snippets",
     ":test_support",
     "//base",
     "//base/test:test_support",
     "//components/bookmarks/browser",
     "//components/bookmarks/test",
     "//components/image_fetcher",
@@ skipping 39 matching lines @@
 
   deps = [
     ":ntp_snippets",
     "//base",
     "//components/offline_pages/core",
     "//components/offline_pages/core:test_support",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }