[Sensors] Consider maximum supported frequency

device/generic_sensor/platform_sensor.h

Index: device/generic_sensor/platform_sensor.h
diff --git a/device/generic_sensor/platform_sensor.h b/device/generic_sensor/platform_sensor.h
index 0a2948ffb48b63989dd92509b602b730ebf7735c..d4785f2978c46c87f7074e4979ba716ea0baaaa6 100644
--- a/device/generic_sensor/platform_sensor.h
+++ b/device/generic_sensor/platform_sensor.h
@@ -41,6 +41,12 @@ class DEVICE_GENERIC_SENSOR_EXPORT PlatformSensor
   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,