Minor ObjC header updates.

webrtc/base/objc/RTCFileLogger.h

Index: webrtc/base/objc/RTCFileLogger.h
diff --git a/webrtc/base/objc/RTCFileLogger.h b/webrtc/base/objc/RTCFileLogger.h
index c736012c25f6ec267e2b60e03ffc211e8c63b007..281be4e31ff76fb08ab11e230dee0e5069ebf56a 100644
--- a/webrtc/base/objc/RTCFileLogger.h
+++ b/webrtc/base/objc/RTCFileLogger.h
@@ -11,17 +11,19 @@
 #import <Foundation/Foundation.h>
 
 typedef NS_ENUM(NSUInteger, RTCFileLoggerSeverity) {
-  kRTCFileLoggerSeverityVerbose,
-  kRTCFileLoggerSeverityInfo,
-  kRTCFileLoggerSeverityWarning,
-  kRTCFileLoggerSeverityError
+  RTCFileLoggerSeverityVerbose,
+  RTCFileLoggerSeverityInfo,
+  RTCFileLoggerSeverityWarning,
+  RTCFileLoggerSeverityError
 };
 
 typedef NS_ENUM(NSUInteger, RTCFileLoggerRotationType) {
-  kRTCFileLoggerTypeCall,
-  kRTCFileLoggerTypeApp,
+  RTCFileLoggerTypeCall,
+  RTCFileLoggerTypeApp,
 };
 
+NS_ASSUME_NONNULL_BEGIN
+
 // This class intercepts WebRTC logs and saves them to a file. The file size
 // will not exceed the given maximum bytesize. When the maximum bytesize is
 // reached, logs are rotated according to the rotationType specified.
@@ -67,3 +69,6 @@ typedef NS_ENUM(NSUInteger, RTCFileLoggerRotationType) {
 - (NSData *)logData;
 
 @end
+
+NS_ASSUME_NONNULL_END
+