[Sensors] Simplify calculation of the reporting period

third_party/WebKit/Source/modules/sensor/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 Sensor_h
 #define Sensor_h
 
 #include "core/dom/ContextLifecycleObserver.h"
 #include "core/dom/DOMHighResTimeStamp.h"
 #include "core/dom/DOMTimeStamp.h"
@@ skipping 63 matching lines @@
   // parameters if needed.
   virtual SensorConfigurationPtr CreateSensorConfig();
 
   double ReadingValue(int index, bool& is_null) const;
   double ReadingValueUnchecked(int index) const;
   bool CanReturnReadings() const;
   bool IsActivated() const { return state_ == SensorState::kActivated; }
 
   // SensorProxy::Observer overrides.
   void OnSensorInitialized() override;
-  void OnSensorReadingChanged(double timestamp) override;
+  void OnSensorReadingChanged() override;
   void OnSensorError(ExceptionCode,
                      const String& sanitized_message,
                      const String& unsanitized_message) override;
 
  private:
   void InitSensorProxyIfNeeded();
 
   // ContextLifecycleObserver overrides.
   void ContextDestroyed(ExecutionContext*) override;
 
@@ skipping 13 matching lines @@
   void NotifyOnActivate();
   void NotifyError(DOMException* error);
 
  private:
   SensorOptions sensor_options_;
   device::mojom::blink::SensorType type_;
   SensorState state_;
   Member<SensorProxy> sensor_proxy_;
   device::SensorReading reading_;
   SensorConfigurationPtr configuration_;
-  double last_update_timestamp_;
   bool pending_reading_update_;
 };
 
 }  // namespace blink
 
 #endif  // Sensor_h