Introduce ThresholdCurve (avoids code duplication between PLR/RPLR-based FecController)

webrtc/modules/audio_coding/BUILD.gn

 # Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 import("../../webrtc.gni")
 import("audio_coding.gni")
@@ skipping 898 matching lines @@
     "audio_network_adaptor/dtx_controller.h",
     "audio_network_adaptor/event_log_writer.cc",
     "audio_network_adaptor/event_log_writer.h",
     "audio_network_adaptor/fec_controller_plr_based.cc",
     "audio_network_adaptor/fec_controller_plr_based.h",
     "audio_network_adaptor/fec_controller_rplr_based.cc",
     "audio_network_adaptor/fec_controller_rplr_based.h",
     "audio_network_adaptor/frame_length_controller.cc",
     "audio_network_adaptor/frame_length_controller.h",
     "audio_network_adaptor/include/audio_network_adaptor.h",
+    "audio_network_adaptor/util/threshold_curve.h",
   ]
 
   deps = [
     "../..:webrtc_common",
     "../../base:rtc_base_approved",
     "../../common_audio",
     "../../logging:rtc_event_log_api",
     "../../system_wrappers",
   ]
 
@@ skipping 1059 matching lines @@
       "audio_network_adaptor/bitrate_controller_unittest.cc",
       "audio_network_adaptor/channel_controller_unittest.cc",
       "audio_network_adaptor/controller_manager_unittest.cc",
       "audio_network_adaptor/dtx_controller_unittest.cc",
       "audio_network_adaptor/event_log_writer_unittest.cc",
       "audio_network_adaptor/fec_controller_plr_based_unittest.cc",
       "audio_network_adaptor/fec_controller_rplr_based_unittest.cc",
       "audio_network_adaptor/frame_length_controller_unittest.cc",
       "audio_network_adaptor/mock/mock_controller.h",
       "audio_network_adaptor/mock/mock_controller_manager.h",
+      "audio_network_adaptor/util/threshold_curve_unittest.cc",
       "codecs/builtin_audio_decoder_factory_unittest.cc",
       "codecs/cng/audio_encoder_cng_unittest.cc",
       "codecs/cng/cng_unittest.cc",
       "codecs/ilbc/ilbc_unittest.cc",
       "codecs/isac/fix/source/filterbanks_unittest.cc",
       "codecs/isac/fix/source/filters_unittest.cc",
       "codecs/isac/fix/source/lpc_masking_model_unittest.cc",
       "codecs/isac/fix/source/transform_unittest.cc",
       "codecs/isac/main/source/audio_encoder_isac_unittest.cc",
       "codecs/isac/main/source/isac_unittest.cc",
@@ skipping 122 matching lines @@
 # webrtc/api/audio_codecs:builtin_audio_decoder_factory instead.
 # TODO(kwiberg): Remove this.
 rtc_source_set("builtin_audio_decoder_factory") {
   sources = [
     "codecs/builtin_audio_decoder_factory.h",
   ]
   deps = [
     "../../api/audio_codecs:builtin_audio_decoder_factory",
   ]
 }