Factor out GamepadCommon base class from Gamepad and WebKitGamepad

Source/modules/gamepad/WebKitGamepadList.cpp

Index: Source/modules/gamepad/WebKitGamepadList.cpp
diff --git a/Source/modules/gamepad/WebKitGamepadList.cpp b/Source/modules/gamepad/WebKitGamepadList.cpp
index da3cec035cfa7c6f3c9422ced08e90c92eb9dedf..765f77c1b31e830c0cde0fccfa1c492e6aabc1ba 100644
--- a/Source/modules/gamepad/WebKitGamepadList.cpp
+++ b/Source/modules/gamepad/WebKitGamepadList.cpp
@@ -7,10 +7,6 @@
 
 namespace WebCore {
 
-WebKitGamepadList::~WebKitGamepadList()
-{
-}
-
 void WebKitGamepadList::set(unsigned index, PassRefPtrWillBeRawPtr<WebKitGamepad> gamepad)
 {
     if (index >= blink::WebGamepads::itemsLengthCap)
@@ -18,21 +14,9 @@ void WebKitGamepadList::set(unsigned index, PassRefPtrWillBeRawPtr<WebKitGamepad
     m_items[index] = gamepad;
 }
 
-unsigned WebKitGamepadList::length() const
-{
-    return blink::WebGamepads::itemsLengthCap;
-}
-
 WebKitGamepad* WebKitGamepadList::item(unsigned index)
 {
     return index < length() ? m_items[index].get() : 0;
 }
 
-void WebKitGamepadList::trace(Visitor* visitor)
-{
-    for (unsigned index = 0; index < blink::WebGamepads::itemsLengthCap; index++) {
-        visitor->trace(m_items[index]);
-    }
-}
-
 } // namespace WebCore