Default-enable deferred sequence numbering for video.

Bug: webrtc:11340, webrtc:12470
Change-Id: I1a2a2a33be8720ecb7dbaf4ce8466c5257e8e0ee
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/227774
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Commit-Queue: Erik Språng <sprang@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34663}
diff --git a/call/rtp_video_sender.cc b/call/rtp_video_sender.cc
index 5b6712d..7f0e9da 100644
--- a/call/rtp_video_sender.cc
+++ b/call/rtp_video_sender.cc
@@ -231,6 +231,8 @@
       crypto_options.sframe.require_frame_encryption;
   configuration.extmap_allow_mixed = rtp_config.extmap_allow_mixed;
   configuration.rtcp_report_interval_ms = rtcp_report_interval_ms;
+  configuration.use_deferred_sequencing = !absl::StartsWith(
+      trials.Lookup("WebRTC-Video-DeferredSequencing"), "Disabled");
   configuration.field_trials = &trials;
 
   std::vector<RtpStreamSender> rtp_streams;