Fix incorrect example in mod_ops.h

webrtc/base/mod_ops.h

 /*
  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 25 matching lines @@
     return M - (sub - a);
   return a - sub;
 }
 
 // Calculates the forward difference between two wrapping numbers.
 //
 // Example:
 // uint8_t x = 253;
 // uint8_t y = 2;
 //
-// ForwardDiff(x, y) == 4
+// ForwardDiff(x, y) == 5
 //
 //   252   253   254   255    0     1     2     3
 // #################################################
 // |     |  x  |     |     |     |     |  y  |     |
 // #################################################
 //          |----->----->----->----->----->
 //
 // ForwardDiff(y, x) == 251
 //
 //   252   253   254   255    0     1     2     3
@@ skipping 69 matching lines @@
 template <typename T>
 inline T MinDiff(T a, T b) {
   static_assert(std::is_unsigned<T>::value,
                 "Type must be an unsigned integer.");
   return std::min(ForwardDiff(a, b), ReverseDiff(a, b));
 }
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_BASE_MOD_OPS_H_