remote_suggestions_provider_impl_unittest.cc: Remove unused code

components/ntp_snippets/remote/remote_suggestions_provider_impl_unittest.cc

Index: components/ntp_snippets/remote/remote_suggestions_provider_impl_unittest.cc
diff --git a/components/ntp_snippets/remote/remote_suggestions_provider_impl_unittest.cc b/components/ntp_snippets/remote/remote_suggestions_provider_impl_unittest.cc
index 6716ef405eba776ddef932d205b954b113796c55..446524621abd8bcbdd58ba97155b922f202bceb3 100644
--- a/components/ntp_snippets/remote/remote_suggestions_provider_impl_unittest.cc
+++ b/components/ntp_snippets/remote/remote_suggestions_provider_impl_unittest.cc
@@ -89,10 +89,6 @@ MATCHER_P(IdWithinCategoryEq, expected_id, "") {
   return arg.id().id_within_category() == expected_id;
 }
 
-MATCHER_P(IsCategory, id, "") {
-  return arg.id() == static_cast<int>(id);
-}
-
 MATCHER_P(HasCode, code, "") {
   return arg.code == code;
 }