Factor out GamepadCommon base class from Gamepad and WebKitGamepad

Source/modules/gamepad/WebKitGamepad.h

Index: Source/modules/gamepad/WebKitGamepad.h
diff --git a/Source/modules/gamepad/WebKitGamepad.h b/Source/modules/gamepad/WebKitGamepad.h
index dff3f72d729492d1afde8392e5be50459e91a885..e724d95683450b780299378573d7d8219bf23685 100644
--- a/Source/modules/gamepad/WebKitGamepad.h
+++ b/Source/modules/gamepad/WebKitGamepad.h
@@ -7,14 +7,13 @@
 
 #include "bindings/v8/ScriptWrappable.h"
 #include "heap/Handle.h"
-#include "public/platform/WebGamepad.h"
+#include "modules/gamepad/GamepadCommon.h"
 #include "wtf/RefCounted.h"
 #include "wtf/Vector.h"
-#include "wtf/text/WTFString.h"
 
 namespace WebCore {
 
-class WebKitGamepad FINAL : public RefCountedWillBeGarbageCollectedFinalized<WebKitGamepad>, public ScriptWrappable {
+class WebKitGamepad FINAL : public RefCountedWillBeGarbageCollectedFinalized<WebKitGamepad>, public GamepadCommon, public ScriptWrappable {
 public:
     static PassRefPtrWillBeRawPtr<WebKitGamepad> create()
     {
@@ -24,37 +23,13 @@ public:
 
     typedef Vector<float> FloatVector;
 
-    const String& id() const { return m_id; }
-    void setId(const String& id) { m_id = id; }
-
-    unsigned index() const { return m_index; }
-    void setIndex(unsigned val) { m_index = val; }
-
-    bool connected() const { return m_connected; }
-    void setConnected(bool val) { m_connected = val; }
-
-    unsigned long long timestamp() const { return m_timestamp; }
-    void setTimestamp(unsigned long long val) { m_timestamp = val; }
-
-    const String& mapping() const { return m_mapping; }
-    void setMapping(const String& val) { m_mapping = val; }
-
-    const FloatVector& axes() const { return m_axes; }
-    void setAxes(unsigned count, const float* data);
-
     const FloatVector& buttons() const { return m_buttons; }
     void setButtons(unsigned count, const blink::WebGamepadButton* data);
 
-    void trace(Visitor*);
+    void trace(Visitor*) { }
 
 private:
     WebKitGamepad();
-    String m_id;
-    unsigned m_index;
-    bool m_connected;
-    unsigned long long m_timestamp;
-    String m_mapping;
-    FloatVector m_axes;
     FloatVector m_buttons;
 };