Reland of BWE allocation strategy

TBR=stefan@webrtc.org,alexnarest@webrtc.org

Bug: webrtc:8243
Change-Id: Ie68e4f414b2ac32ba4e64877cb250fabcb089a07
Reviewed-on: https://webrtc-review.googlesource.com/13940
Commit-Queue: Alex Narest <alexnarest@webrtc.org>
Reviewed-by: Alex Narest <alexnarest@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20369}

sdk/objc/Framework/Classes/PeerConnection/RTCPeerConnection.mm

@@ -21,6 +21,7 @@
 #import "RTCRtpReceiver+Private.h"
 #import "RTCRtpSender+Private.h"
 #import "RTCSessionDescription+Private.h"
+#import "WebRTC/RTCBitrateAllocationStrategy.h"
 #import "WebRTC/RTCLogging.h"
 
 #include <memory>
@@ -385,6 +386,15 @@ void PeerConnectionDelegateAdapter::OnIceCandidatesRemoved(
   return _peerConnection->SetBitrate(params).ok();
 }
 
+- (void)setBitrateAllocationStrategy:
+        (RTCBitrateAllocationStrategy *_Nullable)bitrateAllocationStrategy {
+  if (bitrateAllocationStrategy)
+    _peerConnection->SetBitrateAllocationStrategy(
+        std::unique_ptr<rtc::BitrateAllocationStrategy>(bitrateAllocationStrategy.strategy));
+  else
+    _peerConnection->SetBitrateAllocationStrategy(nullptr);
+}
+
 - (BOOL)startRtcEventLogWithFilePath:(NSString *)filePath
                       maxSizeInBytes:(int64_t)maxSizeInBytes {
   RTC_DCHECK(filePath.length);