Clean up forward declarations in Source/modules

Source/modules/device_orientation/DeviceMotionController.h

 // Copyright 2014 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 DeviceMotionController_h
 #define DeviceMotionController_h
 
 #include "core/dom/DocumentSupplementable.h"
 #include "core/frame/DeviceSingleWindowEventController.h"
 
 namespace blink {
 
-class DeviceMotionData;
 class Event;
 
 class DeviceMotionController final : public DeviceSingleWindowEventController, public DocumentSupplement {
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(DeviceMotionController);
 public:
     virtual ~DeviceMotionController();
 
     static const char* supplementName();
     static DeviceMotionController& from(Document&);
 
     virtual void trace(Visitor*) override;
 
 private:
     explicit DeviceMotionController(Document&);
 
     // Inherited from DeviceEventControllerBase.
     virtual void registerWithDispatcher() override;
     virtual void unregisterWithDispatcher() override;
     virtual bool hasLastData() override;
 
     // Inherited from DeviceSingleWindowEventController.
     virtual PassRefPtrWillBeRawPtr<Event> lastEvent() const override;
     virtual const AtomicString& eventTypeName() const override;
     virtual bool isNullEvent(Event*) const override;
 };
 
 } // namespace blink
 
 #endif // DeviceMotionController_h