Expose bit rate property in ARDAppClient and set max bitrate for video RTCRtcSender.

webrtc/examples/objc/AppRTCMobile/ARDAppClient.m

Index: webrtc/examples/objc/AppRTCMobile/ARDAppClient.m
diff --git a/webrtc/examples/objc/AppRTCMobile/ARDAppClient.m b/webrtc/examples/objc/AppRTCMobile/ARDAppClient.m
index 9ef46b4742beb76ca9335230499d13ddfef546f3..e78057815a4f952672246b6f1d86739047290433 100644
--- a/webrtc/examples/objc/AppRTCMobile/ARDAppClient.m
+++ b/webrtc/examples/objc/AppRTCMobile/ARDAppClient.m
@@ -102,6 +102,7 @@ static int64_t const kARDAppClientRtcEventLogMaxSizeInBytes = 5e6;  // 5 MB.
   RTCFileLogger *_fileLogger;
   ARDTimerProxy *_statsTimer;
   RTCMediaConstraints *_cameraConstraints;
+  NSNumber *_maxBitrate;
 }
 
 @synthesize shouldGetStats = _shouldGetStats;
@@ -326,6 +327,10 @@ static int64_t const kARDAppClientRtcEventLogMaxSizeInBytes = 5e6;  // 5 MB.
   _cameraConstraints = mediaConstraints;
 }
 
+- (void)setMaxBitrate:(NSNumber *)maxBitrate {
+  _maxBitrate = maxBitrate;
+}
+
 #pragma mark - ARDSignalingChannelDelegate
 
 - (void)channel:(id<ARDSignalingChannel>)channel
@@ -673,6 +678,9 @@ static int64_t const kARDAppClientRtcEventLogMaxSizeInBytes = 5e6;  // 5 MB.
   RTCRtpSender *sender =
       [_peerConnection senderWithKind:kRTCMediaStreamTrackKindVideo
                              streamId:kARDMediaStreamId];
+
+  [self setMaxBitrate:_maxBitrate forVideoSender:sender];
+
   RTCVideoTrack *track = [self createLocalVideoTrack];
   if (track) {
     sender.track = track;
@@ -681,6 +689,12 @@ static int64_t const kARDAppClientRtcEventLogMaxSizeInBytes = 5e6;  // 5 MB.
   return sender;
 }
 
+- (void)setMaxBitrate:(NSNumber *)maxBitrate forVideoSender:(RTCRtpSender *)sender {
+  for (RTCRtpEncodingParameters *encoding in sender.parameters.encodings) {
+    encoding.maxBitrateBps = maxBitrate;
+  }
+}
+
 - (RTCRtpSender *)createAudioSender {
   RTCMediaConstraints *constraints = [self defaultMediaAudioConstraints];
   RTCAudioSource *source = [_factory audioSourceWithConstraints:constraints];