[NTP::Push] Add feature

components/ntp_snippets/features.h

Index: components/ntp_snippets/features.h
diff --git a/components/ntp_snippets/features.h b/components/ntp_snippets/features.h
index 9946e7c2d0a6c76799eb4123a3f891e1829e06dd..8295e88f9ed732411065e7aa7af226d6e5a3d81f 100644
--- a/components/ntp_snippets/features.h
+++ b/components/ntp_snippets/features.h
@@ -40,6 +40,9 @@ extern const base::Feature kIncreasedVisibility;
 // Feature to prefer AMP URLs over regular URLs when available.
 extern const base::Feature kPreferAmpUrlsFeature;
 
+// Feature to listen for GCM push updates from the server.
+extern const base::Feature kContentSuggestionsPushFeature;
+
 // Feature to choose a category ranker.
 extern const base::Feature kCategoryRanker;