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/modules/video_coding/timing.cc b/modules/video_coding/timing.cc
index a2a4e47..8da2b85 100644
--- a/modules/video_coding/timing.cc
+++ b/modules/video_coding/timing.cc
@@ -28,7 +28,6 @@
       max_playout_delay_ms_(10000),
       jitter_delay_ms_(0),
       current_delay_ms_(0),
-      last_decode_ms_(0),
       prev_frame_timestamp_(0),
       timing_frame_info_(),
       num_decoded_frames_(0) {
@@ -150,14 +149,17 @@
   }
 }
 
-void VCMTiming::StopDecodeTimer(uint32_t time_stamp,
+void VCMTiming::StopDecodeTimer(uint32_t /*time_stamp*/,
                                 int32_t decode_time_ms,
                                 int64_t now_ms,
-                                int64_t render_time_ms) {
+                                int64_t /*render_time_ms*/) {
+  StopDecodeTimer(decode_time_ms, now_ms);
+}
+
+void VCMTiming::StopDecodeTimer(int32_t decode_time_ms, int64_t now_ms) {
   rtc::CritScope cs(&crit_sect_);
   codec_timer_->AddTiming(decode_time_ms, now_ms);
   assert(decode_time_ms >= 0);
-  last_decode_ms_ = decode_time_ms;
   ++num_decoded_frames_;
 }
 
@@ -217,15 +219,13 @@
                   jitter_delay_ms_ + RequiredDecodeTimeMs() + render_delay_ms_);
 }
 
-bool VCMTiming::GetTimings(int* decode_ms,
-                           int* max_decode_ms,
+bool VCMTiming::GetTimings(int* max_decode_ms,
                            int* current_delay_ms,
                            int* target_delay_ms,
                            int* jitter_buffer_ms,
                            int* min_playout_delay_ms,
                            int* render_delay_ms) const {
   rtc::CritScope cs(&crit_sect_);
-  *decode_ms = last_decode_ms_;
   *max_decode_ms = RequiredDecodeTimeMs();
   *current_delay_ms = current_delay_ms_;
   *target_delay_ms = TargetDelayInternal();