Remove public_deps from rtc_base:protobuf_utils.

Bug: webrtc:8603
Change-Id: I8dfc176b570d28ce8003f5f8f1ed995848af9a9d
Reviewed-on: https://webrtc-review.googlesource.com/93761
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Oleh Prypin <oprypin@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24273}
diff --git a/rtc_base/BUILD.gn b/rtc_base/BUILD.gn
index 2b1a34a..cc4d0bc 100644
--- a/rtc_base/BUILD.gn
+++ b/rtc_base/BUILD.gn
@@ -54,7 +54,8 @@
     "protobuf_utils.h",
   ]
   if (rtc_enable_protobuf) {
-    public_deps = [
+    public_configs = [ "//third_party/protobuf:protobuf_config" ]
+    deps = [
       "//third_party/protobuf:protobuf_lite",
     ]
   }