Update API for Objective-C RTCConfiguration.

BUG=

Review URL: https://codereview.webrtc.org/1616303002

Cr-Commit-Position: refs/heads/master@{#11386}
diff --git a/webrtc/api/objc/RTCConfiguration+Private.h b/webrtc/api/objc/RTCConfiguration+Private.h
new file mode 100644
index 0000000..5936ee2
--- /dev/null
+++ b/webrtc/api/objc/RTCConfiguration+Private.h
@@ -0,0 +1,63 @@
+/*
+ *  Copyright 2015 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 "RTCConfiguration.h"
+
+#include "talk/app/webrtc/peerconnectioninterface.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface RTCConfiguration ()
+
+/**
+ * RTCConfiguration struct representation of this RTCConfiguration. This is
+ * needed to pass to the underlying C++ APIs.
+ */
+@property(nonatomic, readonly)
+    webrtc::PeerConnectionInterface::RTCConfiguration nativeConfiguration;
+
+- (instancetype)initWithNativeConfiguration:
+    (webrtc::PeerConnectionInterface::RTCConfiguration)nativeConfiguration;
+
++ (webrtc::PeerConnectionInterface::IceTransportsType)
+    nativeTransportsTypeForTransportPolicy:(RTCIceTransportPolicy)policy;
+
++ (RTCIceTransportPolicy)transportPolicyForTransportsType:
+    (webrtc::PeerConnectionInterface::IceTransportsType)nativeType;
+
++ (NSString *)stringForTransportPolicy:(RTCIceTransportPolicy)policy;
+
++ (webrtc::PeerConnectionInterface::BundlePolicy)nativeBundlePolicyForPolicy:
+    (RTCBundlePolicy)policy;
+
++ (RTCBundlePolicy)bundlePolicyForNativePolicy:
+    (webrtc::PeerConnectionInterface::BundlePolicy)nativePolicy;
+
++ (NSString *)stringForBundlePolicy:(RTCBundlePolicy)policy;
+
++ (webrtc::PeerConnectionInterface::RtcpMuxPolicy)nativeRtcpMuxPolicyForPolicy:
+    (RTCRtcpMuxPolicy)policy;
+
++ (RTCRtcpMuxPolicy)rtcpMuxPolicyForNativePolicy:
+    (webrtc::PeerConnectionInterface::RtcpMuxPolicy)nativePolicy;
+
++ (NSString *)stringForRtcpMuxPolicy:(RTCRtcpMuxPolicy)policy;
+
++ (webrtc::PeerConnectionInterface::TcpCandidatePolicy)
+    nativeTcpCandidatePolicyForPolicy:(RTCTcpCandidatePolicy)policy;
+
++ (RTCTcpCandidatePolicy)tcpCandidatePolicyForNativePolicy:
+    (webrtc::PeerConnectionInterface::TcpCandidatePolicy)nativePolicy;
+
++ (NSString *)stringForTcpCandidatePolicy:(RTCTcpCandidatePolicy)policy;
+
+@end
+
+NS_ASSUME_NONNULL_END