Update third_party/protobuf to protobuf-v3.0.0-beta-3

third_party/protobuf/objectivec/GPBUnknownFieldSet.h

 // Protocol Buffers - Google's data interchange format
 // Copyright 2008 Google Inc.  All rights reserved.
 // https://developers.google.com/protocol-buffers/
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
@@ skipping 16 matching lines @@
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #import <Foundation/Foundation.h>
 
 @class GPBUnknownField;
 
 NS_ASSUME_NONNULL_BEGIN
 
+/// A collection of unknown fields.
 @interface GPBUnknownFieldSet : NSObject<NSCopying>
 
+/// Tests to see if the given field number has a value.
+///
+/// @param number The field number to check.
+///
+/// @return YES if there is an unknown field for the given field number.
 - (BOOL)hasField:(int32_t)number;
+
+/// Fetches the @c GPBUnknownField for the given field number.
+///
+/// @param number The field number to look up.
+///
+/// @return The @c GPBUnknownField or nil.
 - (nullable GPBUnknownField *)getField:(int32_t)number;
+
+/// Returns the number of fields in this set.
 - (NSUInteger)countOfFields;
 
+/// Adds the given field to the set.
 - (void)addField:(GPBUnknownField *)field;
 
-// Returns an NSArray of the GPBFields sorted by the field numbers.
-- (NSArray *)sortedFields;
+/// Returns an NSArray of the @c GPBUnknownFields sorted by the field numbers.
+- (NSArray<GPBUnknownField*> *)sortedFields;
 
 @end
 
 NS_ASSUME_NONNULL_END