blink: Cleanup class forward declarations

third_party/WebKit/Source/modules/sensor/SensorReading.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 SensorReading_h
 #define SensorReading_h
 
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "core/dom/DOMHighResTimeStamp.h"
 #include "core/dom/DOMTimeStamp.h"
 #include "modules/sensor/SensorProxy.h"
 
 namespace blink {
 
-class ExecutionContext;
 class ScriptState;
 
 class SensorReading : public GarbageCollectedFinalized<SensorReading>,
                       public ScriptWrappable {
   DEFINE_WRAPPERTYPEINFO();
 
  public:
   DECLARE_VIRTUAL_TRACE();
 
   DOMHighResTimeStamp timeStamp(ScriptState*) const;
 
   // Returns 'true' if the current reading value is different than the given
   // previous one; otherwise returns 'false'.
   virtual bool isReadingUpdated(const SensorProxy::Reading& previous) const = 0;
 
   virtual ~SensorReading();
 
  protected:
   explicit SensorReading(SensorProxy*);
 
  protected:
   Member<SensorProxy> m_sensorProxy;
 };
 
 }  // namepsace blink
 
 #endif  // SensorReading_h