[PPAPI] Added a new Var subclass, ResourceVar.

ppapi/shared_impl/resource_var.cc

+// 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.
+
+#include "ppapi/shared_impl/resource_var.h"
+
+namespace ppapi {
+
+ResourceVar::ResourceVar() : resource_id_(0) {}
+
+ResourceVar::ResourceVar(PP_Resource resource_id) : resource_id_(resource_id) {}
+
+ResourceVar::~ResourceVar() {}
+
+ResourceVar* ResourceVar::AsResourceVar() {
+  return this;
+}
+
+PP_VarType ResourceVar::GetType() const {
+  // TODO(mgiuca): Return PP_VARTYPE_RESOURCE, once that is a valid enum value.
+  NOTREACHED();
+  return PP_VARTYPE_UNDEFINED;
+}
+
+// static
+ResourceVar* ResourceVar::FromPPVar(PP_Var var) {
+  // TODO(mgiuca): Implement this function, once PP_VARTYPE_RESOURCE is
+  // introduced.
+  return NULL;
+}
+
+}  // namespace ppapi