NetEq: Simplify the dependencies of GetNetworkStatistics

Adds a new method PopulateDelayManagerStats which takes care of the
fields that needed information from the DelayManager.

Also adds a new test for StatisticsCalculator made practically
feasible by the refactoring.

Bug: webrtc:7554
Change-Id: Iff5cb5e209c276bd2784f2ccf73be8f619b1d955
Reviewed-on: https://webrtc-review.googlesource.com/3181
Reviewed-by: Gustaf Ullberg <gustaf@webrtc.org>
Commit-Queue: Henrik Lundin <henrik.lundin@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#19957}

modules/audio_coding/neteq/statistics_calculator.cc

diff --git a/modules/audio_coding/neteq/statistics_calculator.cc b/modules/audio_coding/neteq/statistics_calculator.cc
index 09ced6a..4e034e6 100644
--- a/modules/audio_coding/neteq/statistics_calculator.cc
+++ b/modules/audio_coding/neteq/statistics_calculator.cc
@@ -14,7 +14,6 @@
 #include <string.h>  // memset
 #include <algorithm>
 
-#include "modules/audio_coding/neteq/decision_logic.h"
 #include "modules/audio_coding/neteq/delay_manager.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/safe_conversions.h"
@@ -255,24 +254,13 @@
     int fs_hz,
     size_t num_samples_in_buffers,
     size_t samples_per_packet,
-    const DelayManager& delay_manager,
-    const DecisionLogic& decision_logic,
     NetEqNetworkStatistics *stats) {
-  if (fs_hz <= 0 || !stats) {
-    assert(false);
-    return;
-  }
+  RTC_DCHECK_GT(fs_hz, 0);
+  RTC_DCHECK(stats);
 
   stats->added_zero_samples = added_zero_samples_;
   stats->current_buffer_size_ms =
       static_cast<uint16_t>(num_samples_in_buffers * 1000 / fs_hz);
-  const int ms_per_packet = rtc::dchecked_cast<int>(
-      decision_logic.packet_length_samples() / (fs_hz / 1000));
-  stats->preferred_buffer_size_ms = (delay_manager.TargetLevel() >> 8) *
-      ms_per_packet;
-  stats->jitter_peaks_found = delay_manager.PeakFound();
-  stats->clockdrift_ppm =
-      rtc::saturated_cast<int32_t>(delay_manager.EstimatedClockDriftPpm());
 
   stats->packet_loss_rate =
       CalculateQ14Ratio(lost_timestamps_, timestamps_since_last_report_);
@@ -331,6 +319,18 @@
   Reset();
 }
 
+void StatisticsCalculator::PopulateDelayManagerStats(
+    int ms_per_packet,
+    const DelayManager& delay_manager,
+    NetEqNetworkStatistics* stats) {
+  RTC_DCHECK(stats);
+  stats->preferred_buffer_size_ms =
+      (delay_manager.TargetLevel() >> 8) * ms_per_packet;
+  stats->jitter_peaks_found = delay_manager.PeakFound();
+  stats->clockdrift_ppm =
+      rtc::saturated_cast<int32_t>(delay_manager.EstimatedClockDriftPpm());
+}
+
 NetEqLifetimeStatistics StatisticsCalculator::GetLifetimeStatistics() const {
   return lifetime_stats_;
 }