Add AlrDetector

webrtc/modules/pacing/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("../../build/webrtc.gni")
 
 rtc_static_library("pacing") {
   sources = [
+    "alr_detector.cc",
+    "alr_detector.h",
     "bitrate_prober.cc",
     "bitrate_prober.h",
     "paced_sender.cc",
     "paced_sender.h",
     "packet_router.cc",
     "packet_router.h",
   ]
 
   if (is_clang) {
     # Suppress warnings from Chrome's Clang plugins.
     # See http://code.google.com/p/webrtc/issues/detail?id=163 for details.
     suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
   }
 
   deps = [
     "../../system_wrappers",
     "../bitrate_controller",
     "../rtp_rtcp",
   ]
 }