Remove deprecated thread checker

Bug: webrtc:12419
Change-Id: Ie617a15c29a6b250a4c1bf36da113bb6d5b41d1f
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/206642
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Artem Titov <titovartem@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33216}
diff --git a/api/BUILD.gn b/api/BUILD.gn
index fba4411..0a6c670 100644
--- a/api/BUILD.gn
+++ b/api/BUILD.gn
@@ -175,6 +175,7 @@
     ":rtp_parameters",
     ":rtp_transceiver_direction",
     ":scoped_refptr",
+    ":sequence_checker",
     "../rtc_base:network_constants",
     "adaptation:resource_adaptation_api",
     "audio:audio_mixer_api",