Revert "Avoid critsect for protection- and qm setting callbacks in VideoSender."

This reverts commit 903c0f2e7649a2b98659286dc228447facd49bb7,
aka #8899.

TBR=pbos@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/46759004

Cr-Commit-Position: refs/heads/master@{#8901}

webrtc/modules/rtp_rtcp/source/rtp_sender_unittest.cc

@@ -1346,7 +1346,7 @@ TEST_F(RtpSenderVideoTest, SendVideoWithCVO) {
 
   rtp_sender_video_->SendVideo(kRtpVideoGeneric, kVideoFrameKey, kPayload,
                                kTimestamp, 0, packet_, sizeof(packet_), NULL,
-                               &hdr);
+                               NULL, &hdr);
 
   RtpHeaderExtensionMap map;
   map.Register(kRtpExtensionVideoRotation, kVideoRotationExtensionId);