Add Rtcp parameters for PeerConnection senders

Bug: webrtc:7580
Change-Id: Ibcf5e849a1f11f21fa75f6d006fecf1cd54f8552
Reviewed-on: https://webrtc-review.googlesource.com/78063
Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org>
Reviewed-by: Kári Helgason <kthelgason@webrtc.org>
Commit-Queue: Florent Castelli <orphis@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23407}

sdk/objc/Framework/Classes/PeerConnection/RTCRtcpParameters+Private.h

@@ -0,0 +1,27 @@
+/*
+ *  Copyright 2018 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 "WebRTC/RTCRtcpParameters.h"
+
+#include "api/rtpparameters.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface RTCRtcpParameters ()
+
+/** Returns the equivalent native RtcpParameters structure. */
+@property(nonatomic, readonly) webrtc::RtcpParameters nativeParameters;
+
+/** Initialize the object with a native RtcpParameters structure. */
+- (instancetype)initWithNativeParameters:(const webrtc::RtcpParameters &)nativeParameters;
+
+@end
+
+NS_ASSUME_NONNULL_END