[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 f3befcb8bac97b043b1201737dfb3e19947cecf1..240028a416fe6b265ec17990507d308f0e229910 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,
@@ -328,8 +327,7 @@ 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_;