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 56d76a6829ab2a3e72169fe828020b6626cd5cb1..44ad522fdb2df6e248d059d9823fffe8a4f70a88 100644
--- a/components/search_engines/template_url_prepopulate_data.cc
+++ b/components/search_engines/template_url_prepopulate_data.cc
@@ -1041,6 +1041,19 @@ 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(