[sensors] Add Generic Sensor platform unit tests.

device/generic_sensor/platform_sensor_configuration.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_CONFIGURATION_H_
 #define DEVICE_GENERIC_SENSOR_PLATFORM_SENSOR_CONFIGURATION_H_
 
 #include "base/logging.h"
 
 namespace device {
 
 class PlatformSensorConfiguration {
  public:
   PlatformSensorConfiguration();
   explicit PlatformSensorConfiguration(double frequency);
   ~PlatformSensorConfiguration();
 
   bool operator==(const PlatformSensorConfiguration& other) const;
+  virtual bool operator>(const PlatformSensorConfiguration& other) const;
 
   void set_frequency(double frequency) {
     DCHECK(frequency_ <= kMaxAllowedFrequency && frequency_ > 0.0);
     frequency_ = frequency;
   }
 
   double frequency() const { return frequency_; }
 
   static constexpr double kMaxAllowedFrequency = 60.0;
 
  private:
   double frequency_ = 1.0;  // 1 Hz by default.
 };
 
 }  // namespace device
 
 #endif  // DEVICE_SENSORS_PLATFORM_SENSOR_CONFIGURATION_H_