Make extensions DSE persistent in browser prefs

components/search_engines/template_url_prepopulate_data.cc

Index: components/search_engines/template_url_prepopulate_data.cc
diff --git a/components/search_engines/template_url_prepopulate_data.cc b/components/search_engines/template_url_prepopulate_data.cc
index a8e7fe51514b28e13d90ff06f0b93ed32311ccdc..5900c8819382abefbc0ecdfca6faa3b1f061e639 100644
--- a/components/search_engines/template_url_prepopulate_data.cc
+++ b/components/search_engines/template_url_prepopulate_data.cc
@@ -1037,6 +1037,19 @@ std::vector<std::unique_ptr<TemplateURLData>> GetPrepopulatedEngines(
   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,