Factor out GamepadCommon base class from Gamepad and WebKitGamepad

Source/modules/gamepad/GamepadList.cpp

 /*
  * 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 10 matching lines @@
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
  * DAMAGE.
  */
 
 #include "config.h"
 #include "modules/gamepad/GamepadList.h"
 
 namespace WebCore {
 
+GamepadList::GamepadList()
+{
+    ScriptWrappable::init(this);
+}
+
 GamepadList::~GamepadList()
 {
 }
 
 void GamepadList::set(unsigned index, PassRefPtrWillBeRawPtr<Gamepad> gamepad)
 {
     if (index >= blink::WebGamepads::itemsLengthCap)
         return;
     m_items[index] = gamepad;
 }
 
-unsigned GamepadList::length() const
-{
-    return blink::WebGamepads::itemsLengthCap;
-}
-
 Gamepad* GamepadList::item(unsigned index)
 {
     return index < length() ? m_items[index].get() : 0;
 }
 
 void GamepadList::trace(Visitor* visitor)
 {
     for (unsigned index = 0; index < blink::WebGamepads::itemsLengthCap; index++) {
         visitor->trace(m_items[index]);
     }
 }
 
 } // namespace WebCore