Add ContentSuggestionsCategoryFactory; Store categories as ints

components/ntp_snippets/ntp_snippets_service_unittest.cc

Index: components/ntp_snippets/ntp_snippets_service_unittest.cc
diff --git a/components/ntp_snippets/ntp_snippets_service_unittest.cc b/components/ntp_snippets/ntp_snippets_service_unittest.cc
index 9d56af38b90dc1b5d961c3ee86a7914847bb83a3..6387742b9fe761937bf601f1c35700b54ab3d916 100644
--- a/components/ntp_snippets/ntp_snippets_service_unittest.cc
+++ b/components/ntp_snippets/ntp_snippets_service_unittest.cc
@@ -23,6 +23,7 @@
 #include "base/time/time.h"
 #include "components/image_fetcher/image_decoder.h"
 #include "components/image_fetcher/image_fetcher.h"
+#include "components/ntp_snippets/content_suggestions_category_factory.h"
 #include "components/ntp_snippets/ntp_snippet.h"
 #include "components/ntp_snippets/ntp_snippets_database.h"
 #include "components/ntp_snippets/ntp_snippets_fetcher.h"
@@ -330,15 +331,17 @@ class NTPSnippetsServiceTest : public test::NTPSnippetsTestBase {
         /*image_fetcher=*/nullptr, base::MakeUnique<NTPSnippetsDatabase>(
                                        database_dir_.path(), task_runner),
         base::MakeUnique<NTPSnippetsStatusService>(
-            fake_signin_manager(), mock_sync_service(), pref_service())));
+            fake_signin_manager(), mock_sync_service(), pref_service()),
+        &category_factory_));
 
     if (enabled)
       WaitForDBLoad(service_.get());
   }
 
   std::string MakeUniqueID(const std::string& within_category_id) {
-    return NTPSnippetsService::MakeUniqueID(
-        ContentSuggestionsCategory::ARTICLES, within_category_id);
+    return service()->MakeUniqueID(category_factory_.FromKnownCategory(
+                                       KnownSuggestionsCategories::ARTICLES),
+                                   within_category_id);
   }
 
  protected:
@@ -366,6 +369,7 @@ class NTPSnippetsServiceTest : public test::NTPSnippetsTestBase {
   const GURL test_url_;
   std::unique_ptr<OAuth2TokenService> fake_token_service_;
   MockScheduler scheduler_;
+  ContentSuggestionsCategoryFactory category_factory_;
   // Last so that the dependencies are deleted after the service.
   std::unique_ptr<NTPSnippetsService> service_;