Add test of MakeUniqueID() and friends.

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 85 matching lines @@
       "category_info.h",
       "category_status.h",
     ]
   }
 }
 
 source_set("unit_tests") {
   testonly = true
   sources = [
     "category_factory_unittest.cc",
+    "content_suggestions_provider_unittest.cc",
     "content_suggestions_service_unittest.cc",
     "mock_content_suggestions_provider_observer.cc",
     "mock_content_suggestions_provider_observer.h",
     "ntp_snippet_unittest.cc",
     "ntp_snippets_database_unittest.cc",
     "ntp_snippets_fetcher_unittest.cc",
     "ntp_snippets_service_unittest.cc",
     "ntp_snippets_status_service_unittest.cc",
     "ntp_snippets_test_utils.cc",
     "ntp_snippets_test_utils.h",
@@ skipping 11 matching lines @@
     "//components/signin/core/common",
     "//components/strings",
     "//components/sync:test_support_sync_driver",
     "//components/variations",
     "//net:test_support",
     "//testing/gtest",
     "//third_party/icu/",
     "//ui/gfx:test_support",
   ]
 }