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

device/generic_sensor/platform_sensor_ambient_light_mac.h

+// 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_GENERIC_PLATFORM_SENSOR_AMBIENT_LIGHT_SENSOR_MAC_H_
+#define DEVICE_GENERIC_PLATFORM_SENSOR_AMBIENT_LIGHT_SENSOR_MAC_H_
+
+#include <IOKit/IOKitLib.h>
+
+#include "base/mac/scoped_ionotificationport_ref.h"
+#include "base/mac/scoped_ioobject.h"
+#include "device/generic_sensor/platform_sensor.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}
+
+namespace device {
+
+// Implementation of PlatformSensor for macOS to query the ambient light sensor.
+// This is a single instance object per browser process which is created by
+// The singleton PlatformSensorProviderMac. If there are no clients, this
+// instance is not created.
+class PlatformSensorAmbientLightMac : public PlatformSensor {
+ public:
+  // Construct a platform sensor of |type| AMBIENT_LIGHT, given
+  // a buffer |mapping| to write the result back. |task_runner| is
+  // used to post the notification that the sensor reading has changed.
+  PlatformSensorAmbientLightMac(
+      mojom::SensorType type,
+      mojo::ScopedSharedBufferMapping mapping,
+      PlatformSensorProvider* provider,
+      scoped_refptr<base::SingleThreadTaskRunner> task_runner);
+
+  mojom::ReportingMode GetReportingMode() override;
+  // Can only be called once, the first time or after a StopSensor call.
+  bool StartSensor(const PlatformSensorConfiguration& configuration) override;
+  void StopSensor() override;
+
+ protected:
+  ~PlatformSensorAmbientLightMac() override;
+  bool CheckSensorConfiguration(
+      const PlatformSensorConfiguration& configuration) override;
+  PlatformSensorConfiguration GetDefaultConfiguration() override;
+  void UpdateReading(uint64_t lux_values[2]);
+
+ private:
+  static void IOServiceCallback(void* context,
+                                io_service_t service,
+                                natural_t message_type,
+                                void* message_argument);
+
+  // IOService representing the LMU sensor.
+  base::mac::ScopedIOObject<io_service_t> light_sensor_service_;
+  // Port used to get the notifications from the sensor.
+  base::mac::ScopedIONotificationPortRef light_sensor_port_;
+  // IO Object used to query the value of the sensor.
+  base::mac::ScopedIOObject<io_object_t> light_sensor_object_;
+  // IO Notifications created by IOServiceAddInterestNotification.
+  base::mac::ScopedIOObject<io_object_t> light_sensor_notification_;
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+  double current_lux_;
+
+  DISALLOW_COPY_AND_ASSIGN(PlatformSensorAmbientLightMac);
+};
+
+}  // namespace device
+
+#endif  // DEVICE_GENERIC_PLATFORM_SENSOR_AMBIENT_LIGHT_SENSOR_MAC_H_