Reimplemeted "Test and fix for huge bwe drop after alr state"

webrtc/modules/pacing/alr_detector.cc

 /*
  *  Copyright (c) 2016 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.
  */
 
@@ skipping 85 matching lines @@
                  << settings.alr_bandwidth_usage_percent
                  << ", ALR end budget level percent: "
                  << settings.alr_start_budget_level_percent
                  << ", ALR end budget level percent: "
                  << settings.alr_stop_budget_level_percent;
   }
 
   return ret;
 }
 
+AlrState::Change AlrState::ChangeWhenAlrStartTimeIs(
+    rtc::Optional<int64_t> alr_start_time_ms) {
+  AlrState::Change state_change = AlrState::Change::kNoChange;
+
+  if (was_in_alr_ && !alr_start_time_ms)
+    state_change = AlrState::Change::kEnded;
+
+  if (!was_in_alr_ && alr_start_time_ms)
+    state_change = AlrState::Change::kStarted;
+
+  was_in_alr_ = alr_start_time_ms.has_value();
+
+  return state_change;
+}
+
 }  // namespace webrtc