[Sync] Convert DTCs to be not RefCounted and NonThreadSafe.

components/search_engines/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/features.gni")
 import("//tools/json_to_struct/json_to_struct.gni")
 
 static_library("search_engines") {
   sources = [
     "default_search_manager.cc",
@@ skipping 108 matching lines @@
     "search_host_to_urls_map_unittest.cc",
     "template_url_prepopulate_data_unittest.cc",
     "template_url_service_util_unittest.cc",
     "template_url_unittest.cc",
   ]
 
   deps = [
     ":prepopulated_engines",
     ":test_support",
     "//base",
+    "//base/test:test_support",
     "//components/google/core/browser",
     "//components/pref_registry:test_support",
     "//components/prefs",
     "//components/sync:test_support_sync_api",
     "//components/sync:test_support_sync_driver",
     "//components/syncable_prefs:test_support",
     "//components/webdata/common",
     "//sql",
     "//testing/gmock",
     "//testing/gtest",
@@ skipping 10 matching lines @@
   }
 }
 
 json_to_struct("prepopulated_engines") {
   visibility = [ ":*" ]
 
   source = "prepopulated_engines.json"
   schema_file = "prepopulated_engines_schema.json"
   namespace = "TemplateURLPrepopulateData"
 }