Update ice server provider response format in iOS AppRTCMobile

BUG=webrtc:5963

Review-Url: https://codereview.webrtc.org/2627523004
Cr-Commit-Position: refs/heads/master@{#16050}
diff --git a/webrtc/examples/objc/AppRTCMobile/RTCIceServer+JSON.m b/webrtc/examples/objc/AppRTCMobile/RTCIceServer+JSON.m
index 0bc31bb..912b521 100644
--- a/webrtc/examples/objc/AppRTCMobile/RTCIceServer+JSON.m
+++ b/webrtc/examples/objc/AppRTCMobile/RTCIceServer+JSON.m
@@ -10,34 +10,15 @@
 
 #import "RTCIceServer+JSON.h"
 
-static NSString const *kRTCICEServerUsernameKey = @"username";
-static NSString const *kRTCICEServerPasswordKey = @"password";
-static NSString const *kRTCICEServerUrisKey = @"uris";
-static NSString const *kRTCICEServerUrlKey = @"urls";
-static NSString const *kRTCICEServerCredentialKey = @"credential";
-
 @implementation RTCIceServer (JSON)
 
 + (RTCIceServer *)serverFromJSONDictionary:(NSDictionary *)dictionary {
-  NSString *url = dictionary[kRTCICEServerUrlKey];
-  NSString *username = dictionary[kRTCICEServerUsernameKey];
-  NSString *credential = dictionary[kRTCICEServerCredentialKey];
-  username = username ? username : @"";
-  credential = credential ? credential : @"";
-  return [[RTCIceServer alloc] initWithURLStrings:@[url]
+  NSArray *turnUrls = dictionary[@"urls"];
+  NSString *username = dictionary[@"username"] ?: @"";
+  NSString *credential = dictionary[@"credential"] ?: @"";
+  return [[RTCIceServer alloc] initWithURLStrings:turnUrls
                                          username:username
                                        credential:credential];
 }
 
-+ (RTCIceServer *)serverFromCEODJSONDictionary:(NSDictionary *)dictionary {
-  NSString *username = dictionary[kRTCICEServerUsernameKey];
-  NSString *password = dictionary[kRTCICEServerPasswordKey];
-  NSArray *uris = dictionary[kRTCICEServerUrisKey];
-  RTCIceServer *server =
-      [[RTCIceServer alloc] initWithURLStrings:uris
-                                      username:username
-                                    credential:password];
-  return server;
-}
-
 @end