Refactor DelayManager into separate Histogram class and make it injectable for testing purposes.

Change-Id: I98aa3f992169e598fc1a3dd850400183395fe1fe
Bug: webrtc:10333
Reviewed-on: https://webrtc-review.googlesource.com/c/123445
Commit-Queue: Jakob Ivarsson‎ <jakobi@webrtc.org>
Reviewed-by: Minyue Li <minyue@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26797}
diff --git a/modules/audio_coding/neteq/neteq_impl.cc b/modules/audio_coding/neteq/neteq_impl.cc
index 8115135..9daf296 100644
--- a/modules/audio_coding/neteq/neteq_impl.cc
+++ b/modules/audio_coding/neteq/neteq_impl.cc
@@ -63,11 +63,11 @@
           new DecoderDatabase(decoder_factory, config.codec_pair_id)),
       delay_peak_detector(
           new DelayPeakDetector(tick_timer.get(), config.enable_rtx_handling)),
-      delay_manager(new DelayManager(config.max_packets_in_buffer,
-                                     config.min_delay_ms,
-                                     config.enable_rtx_handling,
-                                     delay_peak_detector.get(),
-                                     tick_timer.get())),
+      delay_manager(DelayManager::Create(config.max_packets_in_buffer,
+                                         config.min_delay_ms,
+                                         config.enable_rtx_handling,
+                                         delay_peak_detector.get(),
+                                         tick_timer.get())),
       dtmf_buffer(new DtmfBuffer(config.sample_rate_hz)),
       dtmf_tone_generator(new DtmfToneGenerator),
       packet_buffer(