Implement new PeerConnection certificate policy API in ObjC API

BUG=webrtc:7088

Review-Url: https://codereview.webrtc.org/2664233002
Cr-Commit-Position: refs/heads/master@{#16424}

webrtc/sdk/objc/Framework/Headers/WebRTC/RTCIceServer.h

@@ -12,6 +12,11 @@
 
 #import <WebRTC/RTCMacros.h>
 
+typedef NS_ENUM(NSUInteger, RTCTlsCertPolicy) {
+  RTCTlsCertPolicySecure,
+  RTCTlsCertPolicyInsecureNoCheck
+};
+
 NS_ASSUME_NONNULL_BEGIN
 
 RTC_EXPORT
@@ -26,6 +31,11 @@ RTC_EXPORT
 /** Credential to use if this RTCIceServer object is a TURN server. */
 @property(nonatomic, readonly, nullable) NSString *credential;
 
+/**
+ * TLS certificate policy to use if this RTCIceServer object is a TURN server.
+ */
+@property(nonatomic, readonly) RTCTlsCertPolicy tlsCertPolicy;
+
 - (nonnull instancetype)init NS_UNAVAILABLE;
 
 /** Convenience initializer for a server with no authentication (e.g. STUN). */
@@ -35,9 +45,18 @@ RTC_EXPORT
  * Initialize an RTCIceServer with its associated URLs, optional username,
  * optional credential, and credentialType.
  */
+- (instancetype)initWithURLStrings:(NSArray<NSString *> *)urlStrings
+                          username:(nullable NSString *)username
+                        credential:(nullable NSString *)credential;
+
+/**
+ * Initialize an RTCIceServer with its associated URLs, optional username,
+ * optional credential, and TLS cert policy.
+ */
 - (instancetype)initWithURLStrings:(NSArray<NSString *> *)urlStrings
                           username:(nullable NSString *)username
                         credential:(nullable NSString *)credential
+                     tlsCertPolicy:(RTCTlsCertPolicy)tlsCertPolicy
     NS_DESIGNATED_INITIALIZER;
 
 @end