[NTP::SectionOrder] Replace CategoryFactory with a category ranker.

components/ntp_snippets/remote/ntp_snippets_fetcher.h

Index: components/ntp_snippets/remote/ntp_snippets_fetcher.h
diff --git a/components/ntp_snippets/remote/ntp_snippets_fetcher.h b/components/ntp_snippets/remote/ntp_snippets_fetcher.h
index 92a23431816d34b462a58ce88849e059101c3318..8c2b802510d44d0561118f3b20c9d813415910e5 100644
--- a/components/ntp_snippets/remote/ntp_snippets_fetcher.h
+++ b/components/ntp_snippets/remote/ntp_snippets_fetcher.h
@@ -138,7 +138,6 @@ class NTPSnippetsFetcher : public OAuth2TokenService::Consumer,
       OAuth2TokenService* token_service,
       scoped_refptr<net::URLRequestContextGetter> url_request_context_getter,
       PrefService* pref_service,
-      CategoryFactory* category_factory,
       translate::LanguageModel* language_model,
       const ParseJSONCallback& parse_json_callback,
       const std::string& api_key,
@@ -330,8 +329,7 @@ class NTPSnippetsFetcher : public OAuth2TokenService::Consumer,
   std::queue<std::pair<RequestBuilder, SnippetsAvailableCallback>>
       pending_requests_;
 
-  // Weak references, not owned.
-  CategoryFactory* const category_factory_;
+  // Weak reference, not owned.
   translate::LanguageModel* const language_model_;
 
   const ParseJSONCallback parse_json_callback_;