Adding codecs to the RtpParameters returned by an RtpSender.

Contains every field except for sdpFmtpLine.
Setting a reordered list of codecs is not yet supported.

R=glaznev@webrtc.org, pthatcher@webrtc.org, skvlad@webrtc.org, tkchin@webrtc.org

Review URL: https://codereview.webrtc.org/1885473004 .

Cr-Commit-Position: refs/heads/master@{#12453}
diff --git a/webrtc/api/objc/RTCRtpCodecParameters+Private.h b/webrtc/api/objc/RTCRtpCodecParameters+Private.h
new file mode 100644
index 0000000..aabbf7d
--- /dev/null
+++ b/webrtc/api/objc/RTCRtpCodecParameters+Private.h
@@ -0,0 +1,30 @@
+/*
+ *  Copyright 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.
+ */
+
+#import <Foundation/Foundation.h>
+
+#import "webrtc/api/objc/RTCRtpCodecParameters.h"
+
+#include "webrtc/api/rtpparameters.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface RTCRtpCodecParameters ()
+
+/** Returns the equivalent native RtpCodecParameters structure. */
+@property(nonatomic, readonly) webrtc::RtpCodecParameters nativeParameters;
+
+/** Initialize the object with a native RtpCodecParameters structure. */
+- (instancetype)initWithNativeParameters:
+    (const webrtc::RtpCodecParameters &)nativeParameters;
+
+@end
+
+NS_ASSUME_NONNULL_END