[Sensors] Align sensor reading attribute implementation with the specification

third_party/WebKit/Source/modules/sensor/AmbientLightSensor.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 AmbientLightSensor_h
 #define AmbientLightSensor_h
 
 #include "modules/sensor/Sensor.h"
 
 namespace blink {
 
 class AmbientLightSensorReading;
 
 class AmbientLightSensor final : public Sensor {
   DEFINE_WRAPPERTYPEINFO();
 
  public:
   static AmbientLightSensor* create(ScriptState*,
                                     const SensorOptions&,
                                     ExceptionState&);
   static AmbientLightSensor* create(ScriptState*, ExceptionState&);
 
   AmbientLightSensorReading* reading() const;
 
   DECLARE_VIRTUAL_TRACE();
 
  private:
   AmbientLightSensor(ScriptState*, const SensorOptions&, ExceptionState&);
   // Sensor overrides.
-  SensorReading* createSensorReading(SensorProxy*) override;
+  std::unique_ptr<SensorReadingFactory> createSensorReadingFactory() override;
   SensorConfigurationPtr createSensorConfig(
       const SensorOptions&,
       const SensorConfiguration& defaultConfig) override;
 };
 
 }  // namespace blink
 
 #endif  // AmbientLightSensor_h