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}

modules/video_coding/generic_decoder_unittest.cc

@@ -30,6 +30,7 @@ class ReceiveCallback : public VCMReceiveCallback {
  public:
   int32_t FrameToRender(VideoFrame& videoFrame,  // NOLINT
                         absl::optional<uint8_t> qp,
+                        int32_t decode_time_ms,
                         VideoContentType content_type) override {
     {
       rtc::CritScope cs(&lock_);