Re-enabling errors on warning, disabling unused parameter warning, and fixing all subsequent errors.
diff --git a/src/core/channel/http_client_filter.c b/src/core/channel/http_client_filter.c
index 4735aa9..96acb38 100644
--- a/src/core/channel/http_client_filter.c
+++ b/src/core/channel/http_client_filter.c
@@ -134,7 +134,7 @@
 }
 
 static const char *scheme_from_args(const grpc_channel_args *args) {
-  int i;
+  unsigned i;
   if (args != NULL) {
     for (i = 0; i < args->num_args; ++i) {
       if (args->args[i].type == GRPC_ARG_STRING &&