mojo: Fix leveldb unittests by making fs::Directories cloneable.

components/filesystem/shared_temp_dir.h

+// Copyright 2016 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 COMPONENTS_FILESYSTEM_SHARED_TEMP_DIR_H_
+#define COMPONENTS_FILESYSTEM_SHARED_TEMP_DIR_H_
+
+#include "base/memory/ref_counted.h"
+
+namespace base {
+class ScopedTempDir;
+}
+
+namespace filesystem {
+
+// A class to allow multiple Directory objects to hold a reference to a
+// temporary directory.
+class SharedTempDir : public base::RefCounted<SharedTempDir> {
+ public:
+  SharedTempDir(std::unique_ptr<base::ScopedTempDir> temp_dir);
+
+ private:
+  friend class base::RefCounted<SharedTempDir>;
+  ~SharedTempDir();
+
+  std::unique_ptr<base::ScopedTempDir> temp_dir_;
+
+  DISALLOW_COPY_AND_ASSIGN(SharedTempDir);
+};
+
+}  // namespace filesystem
+
+#endif  // COMPONENTS_FILESYSTEM_SHARED_TEMP_DIR_H_