Make extensions DSE persistent in browser prefs

components/search_engines/template_url_prepopulate_data.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/template_url_prepopulate_data.h"
 
 #if defined(OS_POSIX) && !defined(OS_MACOSX)
 #include <locale.h>
 #endif
 
@@ skipping 1019 matching lines @@
   // the built-in set.
   *default_search_provider_index = 0;
   std::vector<std::unique_ptr<TemplateURLData>> t_urls =
       GetPrepopulatedTemplateURLData(prefs);
   if (!t_urls.empty())
     return t_urls;
 
   return GetPrepopulationSetFromCountryID(GetCountryIDFromPrefs(prefs));
 }
 
+// Find the prepopulated search engine with the given id.
+std::unique_ptr<TemplateURLData> GetPrepopulatedEngine(PrefService* prefs,
+                                                       int prepopulated_id) {
+  size_t default_index;
+  std::vector<std::unique_ptr<TemplateURLData>> engines =
+      TemplateURLPrepopulateData::GetPrepopulatedEngines(prefs, &default_index);
+  for (auto& engine : engines) {
+    if (engine->prepopulate_id == prepopulated_id)
+      return std::move(engine);
+  }
+  return nullptr;
+}
+
 #if defined(OS_ANDROID)
 std::vector<std::unique_ptr<TemplateURLData>> GetLocalPrepopulatedEngines(
     const std::string& locale,
     PrefService* prefs) {
   int country_id = CountryStringToCountryID(locale);
   if (country_id == kCountryIDUnknown ||
       country_id == GetCountryIDFromPrefs(prefs)) {
     return std::vector<std::unique_ptr<TemplateURLData>>();
   }
 
@@ skipping 104 matching lines @@
   locale_str.erase(0, territory_delim + 1);
 
   // Next remove any codeset/modifier portion and uppercase.
   return CountryStringToCountryID(
       base::ToUpperASCII(locale_str.substr(0, locale_str.find_first_of(".@"))));
 }
 
 #endif  // OS_*
 
 }  // namespace TemplateURLPrepopulateData