RSP2: Rename `delay_counter_` -> `oneway_delay_counter_`

There is a lot of different delays tracked by this class. Renaming this
member clarifies what delay it actually tracks.

Bug: webrtc:15085
Change-Id: I8b038ecf84ca262efdc9f69c0f9a2a9eaad81d37
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/304402
Commit-Queue: Rasmus Brandt <brandtr@webrtc.org>
Reviewed-by: Åsa Persson <asapersson@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#40007}
diff --git a/video/receive_statistics_proxy2.cc b/video/receive_statistics_proxy2.cc
index 4f208a1..f5e6307 100644
--- a/video/receive_statistics_proxy2.cc
+++ b/video/receive_statistics_proxy2.cc
@@ -276,7 +276,7 @@
                                *current_delay_ms);
     log_stream << "WebRTC.Video.CurrentDelayInMs " << *current_delay_ms << '\n';
   }
-  absl::optional<int> delay_ms = delay_counter_.Avg(kMinRequiredSamples);
+  absl::optional<int> delay_ms = oneway_delay_counter_.Avg(kMinRequiredSamples);
   if (delay_ms)
     RTC_HISTOGRAM_COUNTS_10000("WebRTC.Video.OnewayDelayInMs", *delay_ms);
 
@@ -679,9 +679,9 @@
   jitter_buffer_delay_counter_.Add(jitter_buffer_ms);
   target_delay_counter_.Add(target_delay_ms);
   current_delay_counter_.Add(current_delay_ms);
-  // Network delay (rtt/2) + target_delay_ms (jitter delay + decode time +
-  // render delay).
-  delay_counter_.Add(target_delay_ms + avg_rtt_ms_ / 2);
+  // Estimated one-way delay: network delay (rtt/2) + target_delay_ms (jitter
+  // delay + decode time + render delay).
+  oneway_delay_counter_.Add(target_delay_ms + avg_rtt_ms_ / 2);
 }
 
 void ReceiveStatisticsProxy::OnUniqueFramesCounted(int num_unique_frames) {
diff --git a/video/receive_statistics_proxy2.h b/video/receive_statistics_proxy2.h
index 1a2bb77..8613417 100644
--- a/video/receive_statistics_proxy2.h
+++ b/video/receive_statistics_proxy2.h
@@ -175,7 +175,7 @@
   rtc::SampleCounter jitter_buffer_delay_counter_ RTC_GUARDED_BY(main_thread_);
   rtc::SampleCounter target_delay_counter_ RTC_GUARDED_BY(main_thread_);
   rtc::SampleCounter current_delay_counter_ RTC_GUARDED_BY(main_thread_);
-  rtc::SampleCounter delay_counter_ RTC_GUARDED_BY(main_thread_);
+  rtc::SampleCounter oneway_delay_counter_ RTC_GUARDED_BY(main_thread_);
   std::unique_ptr<VideoQualityObserver> video_quality_observer_
       RTC_GUARDED_BY(main_thread_);
   mutable rtc::MovingMaxCounter<int> interframe_delay_max_moving_