Use overloaded operators with QuicTime for addition, subtraction and scalar

net/quic/quic_clock.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/quic_clock.h"
 
 #include "base/time/time.h"
 
 namespace net {
 
@@ skipping 20 matching lines @@
     const QuicWallTime& walltime) const {
   //     ..........................
   //     |            |           |
   // unix epoch   |walltime|   WallNow()
   //     ..........................
   //            |     |           |
   //     clock epoch  |         Now()
   //               result
   //
   // result = Now() - (WallNow() - walltime)
-  return Now().Subtract(QuicTime::Delta::FromMicroseconds(
-      WallNow()
-          .Subtract(
-              QuicTime::Delta::FromMicroseconds(walltime.ToUNIXMicroseconds()))
-          .ToUNIXMicroseconds()));
+  return Now() - QuicTime::Delta::FromMicroseconds(
+                     WallNow()
+                         .Subtract(QuicTime::Delta::FromMicroseconds(
+                             walltime.ToUNIXMicroseconds()))
+                         .ToUNIXMicroseconds());
 }
 
 }  // namespace net