Document VCMTiming::VideoDelayTimings better.

* Reorder and rename members.
* Add comments.
* Define struct first in the class, as per style guide.
* Update direct callers.

Bug: webrtc:15085
Change-Id: I37d26cae1953dacbba7d0507da48e3829ab84ba5
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/304403
Commit-Queue: Rasmus Brandt <brandtr@webrtc.org>
Reviewed-by: Åsa Persson <asapersson@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#40011}

video/video_stream_buffer_controller.cc

diff --git a/video/video_stream_buffer_controller.cc b/video/video_stream_buffer_controller.cc
index c95fb7d..7b1619c 100644
--- a/video/video_stream_buffer_controller.cc
+++ b/video/video_stream_buffer_controller.cc
@@ -319,8 +319,8 @@
   auto timings = timing_->GetTimings();
   if (timings.num_decoded_frames) {
     stats_proxy_->OnFrameBufferTimingsUpdated(
-        timings.max_decode_duration.ms(), timings.current_delay.ms(),
-        timings.target_delay.ms(), timings.jitter_buffer_delay.ms(),
+        timings.estimated_max_decode_time.ms(), timings.current_delay.ms(),
+        timings.target_delay.ms(), timings.jitter_delay.ms(),
         timings.min_playout_delay.ms(), timings.render_delay.ms());
   }
 }