Migrate vr to use inlined tracing

Source/modules/vr/PositionSensorVRDevice.h

 // Copyright 2015 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 PositionSensorVRDevice_h
 #define PositionSensorVRDevice_h
 
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "modules/vr/NavigatorVRDevice.h"
 #include "modules/vr/VRDevice.h"
 #include "modules/vr/VRPositionState.h"
 #include "platform/heap/Handle.h"
 #include "wtf/Forward.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
 class PositionSensorVRDevice final : public VRDevice {
     DEFINE_WRAPPERTYPEINFO();
 public:
     explicit PositionSensorVRDevice(VRHardwareUnit*);
 
     VRPositionState* getState();
     VRPositionState* getImmediateState();
     void resetSensor();
 
-    virtual void trace(Visitor*) override;
+    DECLARE_VIRTUAL_TRACE();
 };
 
 } // namespace blink
 
 #endif // PositionSensorVRDevice_h