From: Andreas Pehrson <apehrson@mozilla.com>
Date: Wed, 18 Oct 2023 17:21:00 +0000
Subject: Bug 1859786 - Fix lock annotation warning in Mozilla-specific edit on
 top of video_capture_impl.cc. r=webrtc-reviewers,mjf

The annotations were added in M116:
https://hg.mozilla.org/mozilla-central/rev/9cd372df013948ad822ae936752d725d77474fb5

Note that this was never unsafe, since _dataCallbacks is only written on the
same thread that we are patching here. This patch however, adds helpful static
analysis.

Differential Revision: https://phabricator.services.mozilla.com/D191301
Mercurial Revision: https://hg.mozilla.org/mozilla-central/rev/56ff441b644400f09d2d0453dbd8991ea25db7b1
---
 modules/video_capture/video_capture_impl.cc | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/modules/video_capture/video_capture_impl.cc b/modules/video_capture/video_capture_impl.cc
index de7fabef55..56efa18968 100644
--- a/modules/video_capture/video_capture_impl.cc
+++ b/modules/video_capture/video_capture_impl.cc
@@ -130,11 +130,14 @@ void VideoCaptureImpl::DeRegisterCaptureDataCallback(
 }
 
 int32_t VideoCaptureImpl::StopCaptureIfAllClientsClose() {
-  if (_dataCallBacks.empty()) {
-    return StopCapture();
-  } else {
-    return 0;
+  RTC_DCHECK_RUN_ON(&api_checker_);
+  {
+    MutexLock lock(&api_lock_);
+    if (!_dataCallBacks.empty()) {
+      return 0;
+    }
   }
+  return StopCapture();
 }
 
 int32_t VideoCaptureImpl::DeliverCapturedFrame(VideoFrame& captureFrame) {