Change behaivor to decide whether a search engine should be shown in the default list

components/search_engines/default_search_pref_migration.cc

 // 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.
 
 #include "components/search_engines/default_search_pref_migration.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <memory>
@@ skipping 50 matching lines @@
   default_provider_data->search_url_post_params =
       prefs->GetString(prefs::kDefaultSearchProviderSearchURLPostParams);
   default_provider_data->suggestions_url_post_params =
       prefs->GetString(prefs::kDefaultSearchProviderSuggestURLPostParams);
   default_provider_data->instant_url_post_params =
       prefs->GetString(prefs::kDefaultSearchProviderInstantURLPostParams);
   default_provider_data->image_url_post_params =
       prefs->GetString(prefs::kDefaultSearchProviderImageURLPostParams);
   default_provider_data->favicon_url =
       GURL(prefs->GetString(prefs::kDefaultSearchProviderIconURL));
-  default_provider_data->show_in_default_list = true;
   default_provider_data->search_terms_replacement_key =
       prefs->GetString(prefs::kDefaultSearchProviderSearchTermsReplacementKey);
   default_provider_data->input_encodings = base::SplitString(
       prefs->GetString(prefs::kDefaultSearchProviderEncodings),
       ";", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
 
   default_provider_data->alternate_urls.clear();
   const base::ListValue* alternate_urls =
       prefs->GetList(prefs::kDefaultSearchProviderAlternateURLs);
   for (size_t i = 0; i < alternate_urls->GetSize(); ++i) {
@@ skipping 79 matching lines @@
 void ConfigureDefaultSearchPrefMigrationToDictionaryValue(
     PrefService* pref_service) {
   if (pref_service->GetInitializationStatus() ==
       PrefService::INITIALIZATION_STATUS_WAITING) {
     pref_service->AddPrefInitObserver(
         base::Bind(&OnPrefsInitialized, base::Unretained(pref_service)));
   } else {
     MigrateDefaultSearchPref(pref_service);
   }
 }