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

webrtc/api/objc/RTCMediaConstraints.h

Index: webrtc/api/objc/RTCMediaConstraints.h
diff --git a/webrtc/api/objc/RTCMediaConstraints.h b/webrtc/api/objc/RTCMediaConstraints.h
index 1ed456cf4eaca788a9c98993a53eb1d577404d5b..a8ad39142e39449d75e9b7b40bad09fb2c421124 100644
--- a/webrtc/api/objc/RTCMediaConstraints.h
+++ b/webrtc/api/objc/RTCMediaConstraints.h
@@ -11,23 +11,17 @@
 #import <Foundation/Foundation.h>
 
 NS_ASSUME_NONNULL_BEGIN
-// TODO(hjon): Update nullability types. See http://crbug/webrtc/5592
 
 @interface RTCMediaConstraints : NSObject
 
-- (nonnull instancetype)init NS_UNAVAILABLE;
+- (instancetype)init NS_UNAVAILABLE;
 
 /** Initialize with mandatory and/or optional constraints. */
-- (nonnull instancetype)initWithMandatoryConstraints:
-    (nullable NSDictionary *)mandatory
-                                 optionalConstraints:
-    (nullable NSDictionary *)optional
+- (instancetype)initWithMandatoryConstraints:
+    (nullable NSDictionary<NSString *, NSString *> *)mandatory
+                         optionalConstraints:
+    (nullable NSDictionary<NSString *, NSString *> *)optional
     NS_DESIGNATED_INITIALIZER;
-// - (instancetype)initWithMandatoryConstraints:
-//     (nullable NSDictionary<NSString *, NSString *> *)mandatory
-//                          optionalConstraints:
-//     (nullable NSDictionary<NSString *, NSString *> *)optional
-//     NS_DESIGNATED_INITIALIZER;
 
 @end