diff --git a/common/clock.h b/common/clock.h
new file mode 100644
index 0000000..2f373a7
--- /dev/null
+++ b/common/clock.h
@@ -0,0 +1,41 @@
+//
+// Copyright (C) 2013 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#ifndef UPDATE_ENGINE_COMMON_CLOCK_H_
+#define UPDATE_ENGINE_COMMON_CLOCK_H_
+
+#include "update_engine/common/clock_interface.h"
+
+namespace chromeos_update_engine {
+
+// Implements a clock.
+class Clock : public ClockInterface {
+ public:
+  Clock() {}
+
+  base::Time GetWallclockTime() override;
+
+  base::Time GetMonotonicTime() override;
+
+  base::Time GetBootTime() override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(Clock);
+};
+
+}  // namespace chromeos_update_engine
+
+#endif  // UPDATE_ENGINE_COMMON_CLOCK_H_