Update base/sys_byteorder.h comment, missed in previous CL.

base/sys_byteorder.h

Index: base/sys_byteorder.h
diff --git a/base/sys_byteorder.h b/base/sys_byteorder.h
index 80bb83199a952ca5c6734c3b1632ea17a0efdabe..500999d6423e7fd4a1d369301f550c954359841a 100644
--- a/base/sys_byteorder.h
+++ b/base/sys_byteorder.h
@@ -2,13 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// This is a convenience header to pull in the platform-specific
-// headers that define functions for byte-order conversion,
-// particularly: ntohs(), htons(), ntohl(), htonl(). Prefer including
-// this file instead of directly writing the #if / #else, since it
-// avoids duplicating the platform-specific selections.
-// This header also provides ntohll() and htonll() for byte-order conversion
-// for 64-bit integers.
+// This header defines cross-platform ByteSwap() implementations for 16, 32 and
+// 64-bit values, and NetToHostXX() / HostToNextXX() functions equivalent to
+// the traditional ntohX() and htonX() functions.
+// Use the functions defined here rather than using the platform-specific
+// functions directly.
 
 #ifndef BASE_SYS_BYTEORDER_H_
 #define BASE_SYS_BYTEORDER_H_