[sensors] [mac] Implement ambient light sensor for macOS

device/sensors/public/cpp/device_sensors_consts.h

Index: device/sensors/public/cpp/device_sensors_consts.h
diff --git a/device/sensors/public/cpp/device_sensors_consts.h b/device/sensors/public/cpp/device_sensors_consts.h
new file mode 100644
index 0000000000000000000000000000000000000000..9bad667e1ad4af118be78ca192a6b89764989446
--- /dev/null
+++ b/device/sensors/public/cpp/device_sensors_consts.h
@@ -0,0 +1,15 @@
+// Copyright 2016 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.
+
+#ifndef DEVICE_SENSORS_PUBLIC_CPP_DEVICE_SENSORS_CONSTS_H_
+#define DEVICE_SENSORS_PUBLIC_CPP_DEVICE_SENSORS_CONSTS_H_
+
+namespace device {
+
+// Default rate for returning value of the ambient light sensor.
+const int kDefaultAmbientLightFrequencyHz = 5;
+
+}  // namespace device
+
+#endif  // DEVICE_SENSORS_PUBLIC_CPP_DEVICE_SENSORS_CONSTS_H_