Revert of Move file_handlers API from //chrome to //extensions

chrome/browser/extensions/api/file_handlers/directory_util.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 CHROME_BROWSER_EXTENSIONS_API_FILE_HANDLERS_DIRECTORY_UTIL_H_
+#define CHROME_BROWSER_EXTENSIONS_API_FILE_HANDLERS_DIRECTORY_UTIL_H_
+
+#include <memory>
+#include <set>
+#include <string>
+#include <vector>
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+
+class Profile;
+
+namespace base {
+class FilePath;
+}  // namespace base
+
+namespace extensions {
+namespace app_file_handler_util {
+
+class IsDirectoryCollector {
+ public:
+  typedef base::Callback<void(std::unique_ptr<std::set<base::FilePath>>)>
+      CompletionCallback;
+
+  explicit IsDirectoryCollector(Profile* profile);
+  virtual ~IsDirectoryCollector();
+
+  // For the given paths obtains a set with which of them are directories.
+  // The collector does not support virtual files if OS != CHROMEOS.
+  void CollectForEntriesPaths(const std::vector<base::FilePath>& paths,
+                              const CompletionCallback& callback);
+
+ private:
+  void OnIsDirectoryCollected(size_t index, bool directory);
+
+  Profile* profile_;
+  std::vector<base::FilePath> paths_;
+  std::unique_ptr<std::set<base::FilePath>> result_;
+  size_t left_;
+  CompletionCallback callback_;
+  base::WeakPtrFactory<IsDirectoryCollector> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(IsDirectoryCollector);
+};
+
+}  // namespace app_file_handler_util
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_API_FILE_HANDLERS_DIRECTORY_UTIL_H_