[PPAPI] Added VarResource_Dev class.

ppapi/cpp/file_system.cc

 // Copyright (c) 2012 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/cpp/file_system.h"
 
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/c/ppb_file_system.h"
 #include "ppapi/cpp/completion_callback.h"
 #include "ppapi/cpp/file_ref.h"
 #include "ppapi/cpp/instance_handle.h"
+#include "ppapi/cpp/logging.h"
 #include "ppapi/cpp/module.h"
 #include "ppapi/cpp/module_impl.h"
 
 namespace pp {
 
 namespace {
 
 template <> const char* interface_name<PPB_FileSystem_1_0>() {
   return PPB_FILESYSTEM_INTERFACE_1_0;
 }
 
 }  // namespace
 
 FileSystem::FileSystem() {
 }
 
 FileSystem::FileSystem(const FileSystem& other) : Resource(other) {
 }
 
+FileSystem::FileSystem(Resource resource) : Resource(resource) {
+  if (!ResourceIsFileSystem(resource)) {
+    PP_NOTREACHED();
+
+    // On release builds, set this to null.
+    Clear();
+  }
+}
+
 FileSystem::FileSystem(PassRef, PP_Resource resource)
     : Resource(PASS_REF, resource) {
 }
 
 FileSystem::FileSystem(const InstanceHandle& instance,
                        PP_FileSystemType type) {
   if (!has_interface<PPB_FileSystem_1_0>())
     return;
   PassRefFromConstructor(get_interface<PPB_FileSystem_1_0>()->Create(
       instance.pp_instance(), type));
 }
 
 int32_t FileSystem::Open(int64_t expected_size,
                          const CompletionCallback& cc) {
   if (!has_interface<PPB_FileSystem_1_0>())
     return cc.MayForce(PP_ERROR_NOINTERFACE);
   return get_interface<PPB_FileSystem_1_0>()->Open(
       pp_resource(), expected_size, cc.pp_completion_callback());
 }
 
+// static
+bool FileSystem::ResourceIsFileSystem(const Resource& resource) {
+  if (!has_interface<PPB_FileSystem_1_0>())
+    return false;
+  return get_interface<PPB_FileSystem_1_0>()->IsFileSystem(
+      resource.pp_resource());
+}
+
 }  // namespace pp