Add no_size_t_to_int_warning suppression to webrtc.

Current set of warnings that need fixing before this warning can
be enabled is here -> https://pastebin.com/raw/jTddgPzP

BUG=chromium:588506, webrtc:9451

Change-Id: Id7896cf48c7231b2ee28dde378ff3ce17da73c2b
Reviewed-on: https://webrtc-review.googlesource.com/96623
Commit-Queue: Will Harris <wfh@chromium.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24503}
diff --git a/webrtc.gni b/webrtc.gni
index 133f86c..c43ebd3 100644
--- a/webrtc.gni
+++ b/webrtc.gni
@@ -238,7 +238,10 @@
 # It sets defines, include paths and compilation warnings accordingly,
 # both for WebRTC stand-alone builds and for the scenario when WebRTC
 # native code is built as part of Chromium.
-rtc_common_configs = [ webrtc_root + ":common_config" ]
+rtc_common_configs = [
+  webrtc_root + ":common_config",
+  "//build/config/compiler:no_size_t_to_int_warning",
+]
 
 if (is_mac || is_ios) {
   rtc_common_configs += [ "//build/config/compiler:enable_arc" ]