Add a Clock and TickClock interface for mocking out time

base/default_clock.cc

Index: base/default_clock.cc
diff --git a/base/default_clock.cc b/base/default_clock.cc
new file mode 100644
index 0000000000000000000000000000000000000000..a2c20cd1100834777790bd5c89fa54888681f201
--- /dev/null
+++ b/base/default_clock.cc
@@ -0,0 +1,27 @@
+// 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 "base/default_clock.h"
+#include "base/lazy_instance.h"
+
+namespace base {
+
+namespace {
+
+LazyInstance<DefaultClock> default_clock = LAZY_INSTANCE_INITIALIZER;

[Ryan Sleevi, 2012/12/17 19:54:46]

DESIGN: Should this be Leaky, to match the worker-safety afforded by
Time::Now/TimeTicks::Now()

[awong, 2012/12/17 19:55:11]

nit: g_default_clock

[akalin, 2012/12/17 22:38:31]

Brett didn't like the lazy instance, so I removed it.

[akalin, 2012/12/17 22:38:31]

removed lazy instance

+
+}  // namespace
+
+DefaultClock::~DefaultClock() {}
+
+Time DefaultClock::Now() {
+  return Time::Now();
+}
+
+// static
+DefaultClock* DefaultClock::Get() {
+  return default_clock.Pointer();
+}
+
+}  // namespace base