Restore type attributes and remove extraneous nullability annotations for Objective-C Mac build

webrtc/api/objc/RTCIceCandidate.h

Index: webrtc/api/objc/RTCIceCandidate.h
diff --git a/webrtc/api/objc/RTCIceCandidate.h b/webrtc/api/objc/RTCIceCandidate.h
index f7e27c21bb3b128e0a32256d01a10d8d90f85cc9..41ea69e9912a59e6417b9bde7c20cd3326066afa 100644
--- a/webrtc/api/objc/RTCIceCandidate.h
+++ b/webrtc/api/objc/RTCIceCandidate.h
@@ -11,7 +11,6 @@
 #import <Foundation/Foundation.h>
 
 NS_ASSUME_NONNULL_BEGIN
-// TODO(hjon): Update nullability types. See http://crbug/webrtc/5592
 
 @interface RTCIceCandidate : NSObject
 
@@ -28,16 +27,16 @@ NS_ASSUME_NONNULL_BEGIN
 @property(nonatomic, readonly) NSInteger sdpMLineIndex;
 
 /** The SDP string for this candidate. */
-@property(nonatomic, readonly, nonnull) NSString *sdp;
+@property(nonatomic, readonly) NSString *sdp;
 
-- (nonnull instancetype)init NS_UNAVAILABLE;
+- (instancetype)init NS_UNAVAILABLE;
 
 /**
  * Initialize an RTCIceCandidate from SDP.
  */
-- (nonnull instancetype)initWithSdp:(nonnull NSString *)sdp
-                      sdpMLineIndex:(NSInteger)sdpMLineIndex
-                             sdpMid:(nullable NSString *)sdpMid
+- (instancetype)initWithSdp:(NSString *)sdp
+              sdpMLineIndex:(NSInteger)sdpMLineIndex
+                     sdpMid:(nullable NSString *)sdpMid
     NS_DESIGNATED_INITIALIZER;
 
 @end