VideoStreamEncoder: expose screenshare UMA stats.

This change adds a few UMAs to inform on the usage of frame
rate constraints related to screenshare sessions.

go/rtc-0hz-present

Bug: chromium:1255737
Change-Id: Icdd011a8e7df837416d603beeb0866d9eb1918e7
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/235368
Commit-Queue: Markus Handell <handellm@webrtc.org>
Reviewed-by: Johannes Kron <kron@webrtc.org>
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#35238}

video/BUILD.gn

@@ -321,8 +321,10 @@ rtc_library("video_stream_encoder_impl") {
     "../rtc_base/system:no_unique_address",
     "../rtc_base/task_utils:pending_task_safety_flag",
     "../rtc_base/task_utils:repeating_task",
+    "../rtc_base/task_utils:to_queued_task",
     "../system_wrappers",
     "../system_wrappers:field_trial",
+    "../system_wrappers:metrics",
     "adaptation:video_adaptation",
   ]
   absl_deps = [

video/video_stream_encoder.cc

@@ -44,9 +44,11 @@
 #include "rtc_base/logging.h"
 #include "rtc_base/strings/string_builder.h"
 #include "rtc_base/system/no_unique_address.h"
+#include "rtc_base/task_utils/to_queued_task.h"
 #include "rtc_base/thread_annotations.h"
 #include "rtc_base/trace_event.h"
 #include "system_wrappers/include/field_trial.h"
+#include "system_wrappers/include/metrics.h"
 #include "video/adaptation/video_stream_encoder_resource_manager.h"
 #include "video/alignment_adjuster.h"
 
@@ -825,6 +827,8 @@ void VideoStreamEncoder::ConfigureEncoder(VideoEncoderConfig config,
         pending_encoder_creation_ =
             (!encoder_ || encoder_config_.video_format != config.video_format ||
              max_data_payload_length_ != max_data_payload_length);
+        if (encoder_config_.content_type != config.content_type)
+          has_reported_screenshare_frame_rate_umas_ = false;
         encoder_config_ = std::move(config);
         max_data_payload_length_ = max_data_payload_length;
         pending_encoder_reconfiguration_ = true;
@@ -1322,6 +1326,7 @@ void VideoStreamEncoder::OnFrame(const VideoFrame& video_frame) {
   encoder_queue_.PostTask(
       [this, incoming_frame, post_time_us, log_stats]() {
         RTC_DCHECK_RUN_ON(&encoder_queue_);
+        MaybeReportFrameRateConstraintUmas();
         encoder_stats_observer_->OnIncomingFrame(incoming_frame.width(),
                                                  incoming_frame.height());
         ++captured_frame_count_;
@@ -2353,6 +2358,64 @@ void VideoStreamEncoder::QueueRequestEncoderSwitch(
   }));
 }
 
+// RTC_RUN_ON(&encoder_queue_)
+void VideoStreamEncoder::MaybeReportFrameRateConstraintUmas() {
+  if (has_reported_screenshare_frame_rate_umas_)
+    return;
+  has_reported_screenshare_frame_rate_umas_ = true;
+  bool is_screenshare =
+      encoder_config_.content_type == VideoEncoderConfig::ContentType::kScreen;
+  if (!is_screenshare)
+    return;
+  main_queue_->PostTask(ToQueuedTask(task_safety_, [this] {
+    RTC_DCHECK_RUN_ON(main_queue_);
+    RTC_HISTOGRAM_BOOLEAN("WebRTC.Screenshare.FrameRateConstraints.Exists",
+                          source_constraints_.has_value());
+    if (source_constraints_.has_value()) {
+      RTC_HISTOGRAM_BOOLEAN(
+          "WebRTC.Screenshare.FrameRateConstraints.Min.Exists",
+          source_constraints_->min_fps.has_value());
+      if (source_constraints_->min_fps.has_value()) {
+        RTC_HISTOGRAM_COUNTS_100(
+            "WebRTC.Screenshare.FrameRateConstraints.Min.Value",
+            source_constraints_->min_fps.value());
+      }
+      RTC_HISTOGRAM_BOOLEAN(
+          "WebRTC.Screenshare.FrameRateConstraints.Max.Exists",
+          source_constraints_->max_fps.has_value());
+      if (source_constraints_->max_fps.has_value()) {
+        RTC_HISTOGRAM_COUNTS_100(
+            "WebRTC.Screenshare.FrameRateConstraints.Max.Value",
+            source_constraints_->max_fps.value());
+      }
+      if (!source_constraints_->min_fps.has_value()) {
+        if (source_constraints_->max_fps.has_value()) {
+          RTC_HISTOGRAM_COUNTS_100(
+              "WebRTC.Screenshare.FrameRateConstraints.MinUnset.Max",
+              source_constraints_->max_fps.value());
+        }
+      } else if (source_constraints_->max_fps.has_value()) {
+        if (source_constraints_->min_fps.value() <
+            source_constraints_->max_fps.value()) {
+          RTC_HISTOGRAM_COUNTS_100(
+              "WebRTC.Screenshare.FrameRateConstraints.MinLessThanMax.Min",
+              source_constraints_->min_fps.value());
+          RTC_HISTOGRAM_COUNTS_100(
+              "WebRTC.Screenshare.FrameRateConstraints.MinLessThanMax.Max",
+              source_constraints_->max_fps.value());
+        }
+        constexpr int kMaxBucketCount =
+            60 * /*max min_fps=*/60 + /*max max_fps=*/60 - 1;
+        RTC_HISTOGRAM_ENUMERATION_SPARSE(
+            "WebRTC.Screenshare.FrameRateConstraints.60MinPlusMaxMinusOne",
+            source_constraints_->min_fps.value() * 60 +
+                source_constraints_->max_fps.value() - 1,
+            /*boundary=*/kMaxBucketCount);
+      }
+    }
+  }));
+}
+
 void VideoStreamEncoder::InjectAdaptationResource(
     rtc::scoped_refptr<Resource> resource,
     VideoAdaptationReason reason) {

video/video_stream_encoder.h

@@ -228,6 +228,9 @@ class VideoStreamEncoder : public VideoStreamEncoderInterface,
   void QueueRequestEncoderSwitch(const webrtc::SdpVideoFormat& format)
       RTC_RUN_ON(&encoder_queue_);
 
+  // Reports UMAs on frame rate constraints usage on the first call.
+  void MaybeReportFrameRateConstraintUmas() RTC_RUN_ON(&encoder_queue_);
+
   TaskQueueBase* const main_queue_;
 
   const uint32_t number_of_cores_;
@@ -244,6 +247,8 @@ class VideoStreamEncoder : public VideoStreamEncoderInterface,
   // The source's constraints.
   absl::optional<VideoTrackSourceConstraints> source_constraints_
       RTC_GUARDED_BY(main_queue_);
+  bool has_reported_screenshare_frame_rate_umas_
+      RTC_GUARDED_BY(&encoder_queue_) = false;
 
   VideoEncoderConfig encoder_config_ RTC_GUARDED_BY(&encoder_queue_);
   std::unique_ptr<VideoEncoder> encoder_ RTC_GUARDED_BY(&encoder_queue_)