[PPAPI] Added VarResource_Dev class.

ppapi/cpp/dev/var_resource_dev.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 PPAPI_CPP_VAR_RESOURCE_DEV_H_
+#define PPAPI_CPP_VAR_RESOURCE_DEV_H_
+
+#include "ppapi/cpp/resource.h"
+#include "ppapi/cpp/var.h"
+
+/// @file
+/// This file defines the API for interacting with resource vars.
+
+namespace pp {
+
+class VarResource_Dev : public Var {
+ public:
+  /// Constructs a <code>VarResource_Dev</code> given a resource.
+  explicit VarResource_Dev(const pp::Resource& resource);
+
+  /// Constructs a <code>VarResource_Dev</code> given a var for which
+  /// is_resource() is true. This will refer to the same resource var, but allow
+  /// you to access methods specific to resources.
+  ///
+  /// @param[in] var A resource var.
+  explicit VarResource_Dev(const Var& var);
+
+  /// Copy constructor.
+  VarResource_Dev(const VarResource_Dev& other);
+
+  virtual ~VarResource_Dev();
+
+  /// Assignment operator.
+  VarResource_Dev& operator=(const VarResource_Dev& other);
+
+  /// The <code>Var</code> assignment operator is overridden here so that we can
+  /// check for assigning a non-resource var to a <code>VarResource_Dev</code>.
+  ///
+  /// @param[in] other The resource var to be assigned.
+  ///
+  /// @return The resulting <code>VarResource_Dev</code> (as a
+  /// <code>Var</code>&).
+  virtual Var& operator=(const Var& other);
+
+  /// Gets the resource contained in the var.
+  ///
+  /// @return The <code>pp::Resource</code> that is contained in the var.
+  pp::Resource AsResource();
+};
+
+}  // namespace pp
+
+#endif  // PPAPI_CPP_VAR_RESOURCE_DEV_H_