Add thread safety annotations for some more PeerConnection members (part 3)

Plus all the annotations that were necessary to make things compile
again.

Bug: webrtc:9987
Change-Id: Ieb363d9ebb47658ecf9138552f44c5bcba6b9b80
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/128775
Reviewed-by: Steve Anton <steveanton@webrtc.org>
Commit-Queue: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27256}
diff --git a/pc/peer_connection.h b/pc/peer_connection.h
index 2d07893..07419bf 100644
--- a/pc/peer_connection.h
+++ b/pc/peer_connection.h
@@ -1125,10 +1125,14 @@
       RTC_GUARDED_BY(signaling_thread());
 
   // These lists store sender info seen in local/remote descriptions.
-  std::vector<RtpSenderInfo> remote_audio_sender_infos_;
-  std::vector<RtpSenderInfo> remote_video_sender_infos_;
-  std::vector<RtpSenderInfo> local_audio_sender_infos_;
-  std::vector<RtpSenderInfo> local_video_sender_infos_;
+  std::vector<RtpSenderInfo> remote_audio_sender_infos_
+      RTC_GUARDED_BY(signaling_thread());
+  std::vector<RtpSenderInfo> remote_video_sender_infos_
+      RTC_GUARDED_BY(signaling_thread());
+  std::vector<RtpSenderInfo> local_audio_sender_infos_
+      RTC_GUARDED_BY(signaling_thread());
+  std::vector<RtpSenderInfo> local_video_sender_infos_
+      RTC_GUARDED_BY(signaling_thread());
 
   SctpSidAllocator sid_allocator_;
   // label -> DataChannel