Fix deadlock in webrtc_perf_tests

webrtc/video/video_quality_test.cc

Index: webrtc/video/video_quality_test.cc
diff --git a/webrtc/video/video_quality_test.cc b/webrtc/video/video_quality_test.cc
index 4357276146f86da57a7d9e3bf50a21e572b95358..37b47867d31db785967a08ef71384862c40651da 100644
--- a/webrtc/video/video_quality_test.cc
+++ b/webrtc/video/video_quality_test.cc
@@ -939,9 +939,11 @@ class VideoAnalyzer : public PacketReceiver,
     // Called when |send_stream_.SetSource()| is called.
     void AddOrUpdateSink(rtc::VideoSinkInterface<VideoFrame>* sink,
                          const rtc::VideoSinkWants& wants) override {
-      rtc::CritScope lock(&crit_);
-      RTC_DCHECK(!send_stream_input_ || send_stream_input_ == sink);
-      send_stream_input_ = sink;
+      {
+        rtc::CritScope lock(&crit_);
+        RTC_DCHECK(!send_stream_input_ || send_stream_input_ == sink);
+        send_stream_input_ = sink;
+      }
       if (video_capturer_) {
         video_capturer_->AddOrUpdateSink(this, wants);
       }