Add a Clock and TickClock interface for mocking out time

base/time/default_tick_clock.cc

Index: base/time/default_tick_clock.cc
diff --git a/base/message_loop_proxy.cc b/base/time/default_tick_clock.cc
similarity index 58%
copy from base/message_loop_proxy.cc
copy to base/time/default_tick_clock.cc
index 755564b9c5d915d71e2fc46f335ec8428db3c769..ce62fcc3d1b33a29fedca396786fe0a3ad1c4c8e 100644
--- a/base/message_loop_proxy.cc
+++ b/base/time/default_tick_clock.cc
@@ -2,16 +2,14 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "base/message_loop_proxy.h"
-
-#include "base/bind.h"
+#include "base/time/default_tick_clock.h"
 
 namespace base {
 
-MessageLoopProxy::MessageLoopProxy() {
-}
+DefaultTickClock::~DefaultTickClock() {}
 
-MessageLoopProxy::~MessageLoopProxy() {
+TimeTicks DefaultTickClock::NowTicks() {
+  return TimeTicks::Now();
 }
 
 }  // namespace base