Fix frames dropped statistics

The |frames_dropped| statistics contain not only frames that are dropped
but also frames that are in internal queues. This CL changes that so
that |frames_dropped| only contains frames that are dropped.

Bug: chromium:990317
Change-Id: If222568501b277a75bc514661c4f8f861b56aaed
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/150111
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Reviewed-by: Niels Moller <nisse@webrtc.org>
Commit-Queue: Johannes Kron <kron@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28968}
diff --git a/call/video_receive_stream.h b/call/video_receive_stream.h
index ad702e6..fa37fe8 100644
--- a/call/video_receive_stream.h
+++ b/call/video_receive_stream.h
@@ -84,6 +84,9 @@
     int min_playout_delay_ms = 0;
     int render_delay_ms = 10;
     int64_t interframe_delay_max_ms = -1;
+    // Frames dropped due to decoding failures or if the system is too slow.
+    // https://www.w3.org/TR/webrtc-stats/#dom-rtcvideoreceiverstats-framesdropped
+    uint32_t frames_dropped = 0;
     uint32_t frames_decoded = 0;
     // https://w3c.github.io/webrtc-stats/#dom-rtcinboundrtpstreamstats-totaldecodetime
     uint64_t total_decode_time_ms = 0;