Introduce injectable NetEqController interface.

This interface is implemented by the DecisionLogic class, which now contains the DelayManager and DelayPeakDetector.

Bug: webrtc:11005
Change-Id: I4fb69fa359e60831cf153e41f101d5b623749380
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/155176
Reviewed-by: Minyue Li <minyue@webrtc.org>
Reviewed-by: Jakob Ivarsson <jakobi@webrtc.org>
Commit-Queue: Ivo Creusen <ivoc@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29613}
diff --git a/modules/audio_coding/neteq/delay_manager.h b/modules/audio_coding/neteq/delay_manager.h
index a701242..f1f24ac 100644
--- a/modules/audio_coding/neteq/delay_manager.h
+++ b/modules/audio_coding/neteq/delay_manager.h
@@ -18,7 +18,6 @@
 
 #include "absl/types/optional.h"
 #include "modules/audio_coding/neteq/histogram.h"
-#include "modules/audio_coding/neteq/statistics_calculator.h"
 #include "modules/audio_coding/neteq/tick_timer.h"
 #include "rtc_base/constructor_magic.h"
 
@@ -41,7 +40,6 @@
                bool enable_rtx_handling,
                DelayPeakDetector* peak_detector,
                const TickTimer* tick_timer,
-               StatisticsCalculator* statistics,
                std::unique_ptr<Histogram> histogram);
 
   // Create a DelayManager object. Notify the delay manager that the packet
@@ -53,8 +51,7 @@
                                               int base_minimum_delay_ms,
                                               bool enable_rtx_handling,
                                               DelayPeakDetector* peak_detector,
-                                              const TickTimer* tick_timer,
-                                              StatisticsCalculator* statistics);
+                                              const TickTimer* tick_timer);
 
   virtual ~DelayManager();
 
@@ -62,10 +59,10 @@
   // |sequence_number| and |timestamp| from the RTP header. This updates the
   // inter-arrival time histogram and other statistics, as well as the
   // associated DelayPeakDetector. A new target buffer level is calculated.
-  // Returns 0 on success, -1 on failure (invalid sample rate).
-  virtual int Update(uint16_t sequence_number,
-                     uint32_t timestamp,
-                     int sample_rate_hz);
+  // Returns the relative delay if it can be calculated.
+  virtual absl::optional<int> Update(uint16_t sequence_number,
+                                     uint32_t timestamp,
+                                     int sample_rate_hz);
 
   // Calculates a new target buffer level. Called from the Update() method.
   // Sets target_level_ (in Q8) and returns the same value. Also calculates
@@ -168,7 +165,6 @@
   const int histogram_quantile_;
   const HistogramMode histogram_mode_;
   const TickTimer* tick_timer_;
-  StatisticsCalculator* statistics_;
   int base_minimum_delay_ms_;
   // Provides delay which is used by LimitTargetLevel as lower bound on target
   // delay.