Prepare AutocompleteController for componentization

components/omnibox/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("//third_party/protobuf/proto_library.gni")
 
 static_library("omnibox") {
   sources = [
     "answers_cache.cc",
     "answers_cache.h",
@@ skipping 80 matching lines @@
   ]
 }
 
 proto_library("in_memory_url_index_cache_proto") {
   sources = [
     "in_memory_url_index_cache.proto",
   ]
 }
 
 static_library("test_support") {
+  testonly = true
   sources = [
+    "mock_autocomplete_provider_client.cc",
+    "mock_autocomplete_provider_client.h",
     "test_scheme_classifier.cc",
     "test_scheme_classifier.h",
   ]
 
   deps = [
     ":omnibox",
     "//base",
     "//components/metrics/proto",
+    "//testing/gmock",
   ]
 }
 
 source_set("unit_tests") {
   testonly = true
   sources = [
     "answers_cache_unittest.cc",
     "autocomplete_input_unittest.cc",
     "autocomplete_match_unittest.cc",
     "autocomplete_result_unittest.cc",
     "base_search_provider_unittest.cc",
     "in_memory_url_index_types_unittest.cc",
     "keyword_provider_unittest.cc",
     "omnibox_field_trial_unittest.cc",
     "suggestion_answer_unittest.cc",
   ]
 
   deps = [
     ":omnibox",
     ":test_support",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }