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;

[Peter Kasting, 2016/12/22 20:49:04]

Nit: Probably should be done in a separate CL, but it seems like this isn't the
only caller that doesn't really care about this value.  Probably
GetPrepopulatedEngines() should change to allow its second arg to be null for
callers that don't care.

[Alexander Yashkin, 2016/12/23 19:44:09]

Agree, it should be done, but in separate CL.

+  std::vector<std::unique_ptr<TemplateURLData>> engines =

[Peter Kasting, 2016/12/22 20:49:04]

Nit: Use auto

[Alexander Yashkin, 2016/12/23 19:44:09]

Done

+      TemplateURLPrepopulateData::GetPrepopulatedEngines(prefs, &default_index);
+  for (auto& engine : engines) {
+    if (engine->prepopulate_id == prepopulated_id)
+      return std::move(engine);
+  }

[Peter Kasting, 2016/12/22 20:49:04]

I tried writing this out with find_if(), but I don't know whether it's better in
the end.  It would probably be better with generic lambdas, but we don't support
C++14.

Up to you if you think this is worth using.

  auto Pred = [prepopulate_id](const std::unique_ptr<TemplateURLData>& data) {
    return data->prepopulate_id == prepopulate_id;
  };
  auto it = std::find_if(engines.begin(), engines.end(), Pred);
  return it == engines.end() ? nullptr : std::move(*it);

[Alexander Yashkin, 2016/12/23 19:44:09]

Old style is more clear here, IMHO.

+  return nullptr;
+}
+
 #if defined(OS_ANDROID)
 
 std::vector<std::unique_ptr<TemplateURLData>> GetLocalPrepopulatedEngines(