BWE allocation strategy

webrtc/examples/objc/AppRTCMobile/ARDBitrateAllocationStrategy.mm

+/*
+ *  Copyright 2017 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 "ARDBitrateAllocationStrategy.h"
+#import "WebRTC/RTCBitrateAllocationStrategy.h"
+
+#include "webrtc/rtc_base/bitrateallocationstrategy.h"
+
+constexpr uint32_t kSufficientAudioBitrate = 16000;
+
+@implementation ARDBitrateAllocationStrategy {
+  rtc::AudioPriorityBitrateAllocationStrategy* audio_priority_strategy_;
+  __weak RTCPeerConnection* _peerConnection;
+}
+
+- (id)init {
+  if (self = [super init]) audio_priority_strategy_ = nullptr;
+  _peerConnection = nil;
+  return self;
+}
+
+- (void)setAudioPriorityStrategy:(RTCPeerConnection*)peerConnection
+                    audioTrackId:(NSString*)audioTrackId {
+  _peerConnection = peerConnection;
+  audio_priority_strategy_ = new rtc::AudioPriorityBitrateAllocationStrategy(
+      std::string(audioTrackId.UTF8String), kSufficientAudioBitrate);
+  [peerConnection setBitrateAllocationStrategy:[[RTCBitrateAllocationStrategy alloc]
+                                                   initWith:audio_priority_strategy_]];
+}
+
+- (void)dealloc {
+  if (_peerConnection) {
+    [_peerConnection setBitrateAllocationStrategy:nil];
+  }
+  if (audio_priority_strategy_) {
+    delete audio_priority_strategy_;
+    audio_priority_strategy_ = nullptr;
+  }
+}
+
+@end