[Sensors] Consider maximum supported frequency

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 OnSensorError() = 0;
     virtual bool IsNotificationSuspended() = 0;
 
    protected:
     virtual ~Client() {}
   };
 
   virtual mojom::ReportingMode GetReportingMode() = 0;
   virtual PlatformSensorConfiguration GetDefaultConfiguration() = 0;
 
+  // Can be overriden to return the sensor maximum reading update frequency
+  // value obtained from the platfrom.
+  // If this information is unavailable '0.0' is returned.

[darktears, 2016/11/02 23:06:09]

This sounds weird. I mean I would expect the default supported frequency to be
60hz unless the platform says different. Then your condition in
AmbientLightSensor.cpp becomes if (frequency > maxSupportedFrequency).

I even wonder if it could be put into PlatformSensorConfiguration instead so
when you get the default config you also get the max supported frequency.

[Mikhail, 2016/11/03 12:13:17]

I'm not sure we should confuse device capabilities and the limitations that come
from our framework at this level. IMO it should rather fall back to the default
frequency if maximum value is not available.

+  // The default implemenmtation returns '0.0'.

[darktears, 2016/11/02 23:06:09]

Typo here.

[Mikhail, 2016/11/03 12:13:17]

Done.

+  virtual double GetMaximumSupportedFrequency();
+
   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*);
@@ skipping 36 matching lines @@
   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_