Factor out GamepadCommon base class from Gamepad and WebKitGamepad

Source/modules/gamepad/Gamepad.h

 /*
  * Copyright (C) 2011, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 18 matching lines @@
 #include "bindings/v8/ScriptWrappable.h"
 #include "heap/Handle.h"
 #include "modules/gamepad/GamepadButton.h"
 #include "public/platform/WebGamepad.h"
 #include "wtf/RefCounted.h"
 #include "wtf/Vector.h"
 #include "wtf/text/WTFString.h"
 
 namespace WebCore {
 
-class Gamepad FINAL : public RefCountedWillBeGarbageCollectedFinalized<Gamepad>, public ScriptWrappable {
+class Gamepad : public RefCountedWillBeGarbageCollectedFinalized<Gamepad>, public ScriptWrappable {
 public:
     static PassRefPtrWillBeRawPtr<Gamepad> create()
     {
         return adoptRefWillBeNoop(new Gamepad);
     }
     ~Gamepad();
 
     typedef Vector<float> FloatVector;
 
     const String& id() const { return m_id; }
@@ skipping 12 matching lines @@
     void setMapping(const String& val) { m_mapping = val; }
 
     const FloatVector& axes() const { return m_axes; }
     void setAxes(unsigned count, const float* data);
 
     const GamepadButtonVector& buttons() const { return m_buttons; }
     void setButtons(unsigned count, const blink::WebGamepadButton* data);
 
     void trace(Visitor*);
 
-private:
+protected:
+    // Inherited by WebKitGamepad
     Gamepad();
     String m_id;
     unsigned m_index;
     bool m_connected;
     unsigned long long m_timestamp;
     String m_mapping;
     FloatVector m_axes;
-    GamepadButtonVector m_buttons;
+
+private:
+    GamepadButtonVector m_buttons; // WebKitGamepad.buttons has different type
 };
 
 } // namespace WebCore
 
 #endif // Gamepad_h