Add a Clock and TickClock interface for mocking out time

base/test/simple_test_clock.cc

Index: base/test/simple_test_clock.cc
diff --git a/base/test/simple_test_clock.cc b/base/test/simple_test_clock.cc
new file mode 100644
index 0000000000000000000000000000000000000000..3bd6080fe9bc0a77a7c633d479aa9ac9caba8ca4
--- /dev/null
+++ b/base/test/simple_test_clock.cc
@@ -0,0 +1,23 @@
+// 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/test/simple_test_clock.h"
+
+namespace base {
+
+SimpleTestClock::SimpleTestClock() {}
+
+SimpleTestClock::~SimpleTestClock() {}
+
+Time SimpleTestClock::Now() {
+  AutoLock lock(lock_);
+  return now_;
+}
+
+void SimpleTestClock::Advance(TimeDelta delta) {
+  AutoLock lock(lock_);
+  now_ += delta;
+}
+
+}  // namespace base