[Sensors] Consider maximum supported frequency

device/generic_sensor/android/java/src/org/chromium/device/sensors/PlatformSensor.java

 // 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.
 
 package org.chromium.device.sensors;
 
 import android.hardware.Sensor;
 import android.hardware.SensorEvent;
 import android.hardware.SensorEventListener;
 import android.os.Build;
 
 import org.chromium.base.annotations.CalledByNative;
 import org.chromium.base.annotations.JNINamespace;
 import org.chromium.device.mojom.ReportingMode;
 
 import java.util.List;
 
 /**
  * Implementation of PlatformSensor that uses Android Sensor Framework. Lifetime is controlled by
  * the device::PlatformSensorAndroid.
  */
 @JNINamespace("device")
 public class PlatformSensor implements SensorEventListener {
     private static final double MICROSECONDS_IN_SECOND = 1000000;
+    private static final double SECONDS_IN_MICROSECOND = 0.000001d;

[timvolodine, 2016/11/03 17:32:55]

why not use import java.util.concurrent.TimeUnit for conversions instead?

[Mikhail, 2016/11/04 21:17:44]

That API operates with 'long' type and loses precision.
https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/TimeUnit.html

     private static final double SECONDS_IN_NANOSECOND = 0.000000001d;
 
     /**
      * The SENSOR_FREQUENCY_NORMAL is defined as 5Hz which corresponds to a polling delay
      * @see android.hardware.SensorManager.SENSOR_DELAY_NORMAL value that is defined as 200000
      * microseconds.
      */
     private static final double SENSOR_FREQUENCY_NORMAL = 5.0d;
 
     /**
@@ skipping 82 matching lines @@
      * Returns default configuration supported by the sensor. Currently only frequency is supported.
      *
      * @return double frequency.
      */
     @CalledByNative
     protected double getDefaultConfiguration() {
         return SENSOR_FREQUENCY_NORMAL;
     }
 
     /**
+     * Returns maximum sampling frequency supported by the sensor.
+     *
+     * @return double frequency in Hz.
+     */
+    @CalledByNative
+    protected double getMaximumSupportedFrequency() {
+        if (mMinDelayUsec == 0) return getDefaultConfiguration();
+        return 1 / (mMinDelayUsec * SECONDS_IN_MICROSECOND);
+    }
+
+    /**
      * Requests sensor to start polling for data.
      *
      * @return boolean true if successful, false otherwise.
      */
     @CalledByNative
     protected boolean startSensor(double frequency) {
         // If we already polling hw with same frequency, do not restart the sensor.
         if (mCurrentPollingFrequency == frequency) return true;
 
         // Unregister old listener if polling frequency has changed.
@@ skipping 82 matching lines @@
                 break;
             default:
                 updateSensorReading(timestamp, event.values[0], event.values[1], event.values[2]);
         }
     }
 
     private native void nativeNotifyPlatformSensorError(long nativePlatformSensorAndroid);
     private native void nativeUpdatePlatformSensorReading(long nativePlatformSensorAndroid,
             double timestamp, double value1, double value2, double value3);
 }