stub webkit/child/ and webkitplatformsupport_child_impl for transition

webkit/child/webkitplatformsupport_child_impl.h

+// // Copyright 2013 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 WEBKIT_CHILD_WEBKITPLATFORMSUPPORT_CHILD_IMPL_H_
+#define WEBKIT_CHILD_WEBKITPLATFORMSUPPORT_CHILD_IMPL_H_
+
+#include "webkit/child/webkit_child_export.h"
+#include "webkit/glue/webkitplatformsupport_impl.h"
+
+namespace webkit_glue {
+
+class WEBKIT_CHILD_EXPORT WebKitPlatformSupportChildImpl :
+    public WebKitPlatformSupportImpl {
+ public:
+  WebKitPlatformSupportChildImpl();
+  virtual ~WebKitPlatformSupportChildImpl();
+};
+
+}  // namespace webkit_glue
+
+#endif  // WEBKIT_CHILD_WEBKITPLATFORMSUPPORT_CHILD_IMPL_H_