SuggestionsService: implement SyncServiceObserver

components/suggestions/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.
 
 source_set("suggestions") {
   sources = [
     "blacklist_store.cc",
     "blacklist_store.h",
     "image_encoder.h",
     "image_fetcher.h",
     "image_fetcher_delegate.h",
     "image_manager.cc",
     "image_manager.h",
     "suggestions_pref_names.cc",
     "suggestions_pref_names.h",
     "suggestions_service.cc",
     "suggestions_service.h",
     "suggestions_store.cc",
     "suggestions_store.h",
-    "suggestions_utils.cc",
-    "suggestions_utils.h",
   ]
 
   public_deps = [
     "//base",
     "//components/prefs",
     "//components/suggestions/proto",
     "//net",
     "//ui/gfx",
     "//url",
   ]
   deps = [
     "//components/data_use_measurement/core",
     "//components/google/core/browser",
     "//components/keyed_service/core",
     "//components/leveldb_proto",
     "//components/pref_registry",
     "//components/signin/core/browser",
+    "//components/sync_driver:sync_driver",
     "//components/variations",
     "//components/variations/net",
     "//google_apis",
   ]
 
   if (is_ios) {
     sources += [ "image_encoder_ios.mm" ]
   } else {
     sources += [ "image_encoder.cc" ]
   }
 }
 
 source_set("unit_tests") {
   testonly = true
   sources = [
     "blacklist_store_unittest.cc",
     "image_manager_unittest.cc",
     "suggestions_service_unittest.cc",
     "suggestions_store_unittest.cc",
   ]
   deps = [
     ":suggestions",
     "//base/test:test_support",
     "//components/leveldb_proto:test_support",
     "//components/pref_registry:test_support",
     "//components/signin/core/browser:test_support",
+    "//components/sync_driver:test_support",
     "//net:test_support",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }