Fix rebase issue of two colliding CLs

Remove the task_safety_ member variable from the video engine header to
resolve a regression introduced during a rebase of two colliding
changes.

Using no-try after verifying that compilation issues have been addressed
so that we can open the tree again.

No-try: true
Bug: none
Change-Id: I5ec3299806c4df8424dfded3b592f3709ba58685
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/461541
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Tomas Gunnarsson <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#47319}

media/engine/webrtc_video_engine.h

diff --git a/media/engine/webrtc_video_engine.h b/media/engine/webrtc_video_engine.h
index 334a871..8c5442b 100644
--- a/media/engine/webrtc_video_engine.h
+++ b/media/engine/webrtc_video_engine.h
@@ -771,7 +771,6 @@
       RTC_GUARDED_BY(thread_checker_);
 
   const int receive_buffer_size_;
-  ScopedTaskSafety task_safety_;
 };
 
 // Keeping the old name "WebRtcVideoChannel" around because some external