Add totalDecodeTime to RTCInboundRTPStreamStats

Pull request to WebRTC stats specification:
https://github.com/w3c/webrtc-stats/pull/450

Bug: webrtc:10775
Change-Id: Id032cb324724329fee284ebc84595b9c39208ab8
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/144035
Commit-Queue: Ilya Nikolaevskiy <ilnik@webrtc.org>
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Reviewed-by: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28440}
diff --git a/pc/rtc_stats_collector_unittest.cc b/pc/rtc_stats_collector_unittest.cc
index 2f0e78b..963a3bc 100644
--- a/pc/rtc_stats_collector_unittest.cc
+++ b/pc/rtc_stats_collector_unittest.cc
@@ -1803,6 +1803,7 @@
   video_media_info.receivers[0].frames_decoded = 8;
   video_media_info.receivers[0].key_frames_decoded = 3;
   video_media_info.receivers[0].qp_sum = absl::nullopt;
+  video_media_info.receivers[0].total_decode_time_ms = 9000;
   video_media_info.receivers[0].last_packet_received_timestamp_ms =
       absl::nullopt;
   video_media_info.receivers[0].content_type = VideoContentType::UNSPECIFIED;
@@ -1840,6 +1841,7 @@
   expected_video.frames_decoded = 8;
   expected_video.key_frames_decoded = 3;
   // |expected_video.qp_sum| should be undefined.
+  expected_video.total_decode_time = 9.0;
   // |expected_video.last_packet_received_timestamp| should be undefined.
   // |expected_video.content_type| should be undefined.