Add RELATIVE_ORIENTATION sensor implementation on macOS to //device/generic_sensor

device/generic_sensor/platform_sensor.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_SENSOR_PLATFORM_SENSOR_H_
 #define DEVICE_GENERIC_SENSOR_PLATFORM_SENSOR_H_
 
 #include <list>
 #include <map>
 
@@ skipping 23 matching lines @@
     virtual void OnSensorReadingChanged() = 0;
     virtual void OnSensorError() = 0;
     virtual bool IsNotificationSuspended() = 0;
 
    protected:
     virtual ~Client() {}
   };
 
   virtual mojom::ReportingMode GetReportingMode() = 0;
   virtual PlatformSensorConfiguration GetDefaultConfiguration() = 0;
+  virtual bool StartSensor(
+      const PlatformSensorConfiguration& configuration) = 0;
+  virtual void StopSensor() = 0;
+  virtual bool CheckSensorConfiguration(
+      const PlatformSensorConfiguration& configuration) = 0;
 
   // Can be overriden to return the sensor maximum sampling frequency
   // value obtained from the platform if it is available. If platfrom
   // does not provide maximum sampling frequency this method must
   // return default frequency.
   // The default implementation returns default frequency.
   virtual double GetMaximumSupportedFrequency();
 
   // Can be overriden to return the sensor minimum sampling frequency.
   // The default implementation returns '1.0 / (60 * 60)', i.e. once per hour.
   virtual double GetMinimumSupportedFrequency();
 
   mojom::SensorType GetType() const;
 
   bool StartListening(Client* client,
                       const PlatformSensorConfiguration& config);
   bool StopListening(Client* client, const PlatformSensorConfiguration& config);
 
   void UpdateSensor();
 
   void AddClient(Client*);
   void RemoveClient(Client*);
 
+  bool GetLatestReading(SensorReading* result);

[Mikhail, 2017/06/21 11:10:00]

let's make it virtual, it seems the newly added
PlatformSensorFusionRelativeOrientation should override it.

[juncai, 2017/07/20 00:22:16]

Not sure why makes it virtual. It should be the same for all subclasses of
PlatformSensor.

+
  protected:
   virtual ~PlatformSensor();
   PlatformSensor(mojom::SensorType type,
                  mojo::ScopedSharedBufferMapping mapping,
                  PlatformSensorProvider* provider);
 
   using ConfigMap = std::map<Client*, std::list<PlatformSensorConfiguration>>;
   using ReadingBuffer = SensorReadingSharedBuffer;
 
   virtual bool UpdateSensorInternal(const ConfigMap& configurations);
-  virtual bool StartSensor(
-      const PlatformSensorConfiguration& configuration) = 0;
-  virtual void StopSensor() = 0;
-  virtual bool CheckSensorConfiguration(
-      const PlatformSensorConfiguration& configuration) = 0;
 
   // Updates shared buffer with new sensor reading data.
   // Note: this method is thread-safe.
   void UpdateSensorReading(const SensorReading& reading, bool notify_clients);
 
   void NotifySensorReadingChanged();
   void NotifySensorError();
 
   // For testing purposes.
   const ConfigMap& config_map() const { return config_map_; }
 
   // Task runner that is used by mojo objects for the IPC.
   // If platfrom sensor events are processed on a different
   // thread, notifications are forwarded to |task_runner_|.
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+  base::ObserverList<Client, true> clients_;
 
  private:
   friend class base::RefCountedThreadSafe<PlatformSensor>;
   const mojo::ScopedSharedBufferMapping shared_buffer_mapping_;
   mojom::SensorType type_;
-  base::ObserverList<Client, true> clients_;
   ConfigMap config_map_;
   PlatformSensorProvider* provider_;
   base::WeakPtrFactory<PlatformSensor> weak_factory_;
   DISALLOW_COPY_AND_ASSIGN(PlatformSensor);
 };
 
 }  // namespace device
 
 #endif  // DEVICE_GENERIC_SENSOR_PLATFORM_SENSOR_H_