Add a Clock and TickClock interface for mocking out time

base/clock.cc

Index: base/clock.cc
diff --git a/chrome/browser/extensions/app_host/app_host_resource.h b/base/clock.cc
similarity index 66%
copy from chrome/browser/extensions/app_host/app_host_resource.h
copy to base/clock.cc
index 29d289cc9fc83f64d4a9cc18bf74ef1dddc28162..9ff65b5f9ead89902f0f918fa8a1233b0041c1d3 100644
--- a/chrome/browser/extensions/app_host/app_host_resource.h
+++ b/base/clock.cc
@@ -2,4 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#define IDI_APP_HOST_MAIN               101
+#include "base/clock.h"
+
+namespace base {
+
+Clock::~Clock() {}
+
+}  // namespace base