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

extensions/browser/api/file_handlers/mime_util.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.
-//
-// This file provides MIME related utilities.
-
-#ifndef EXTENSIONS_BROWSER_API_FILE_HANDLERS_MIME_UTIL_H_
-#define EXTENSIONS_BROWSER_API_FILE_HANDLERS_MIME_UTIL_H_
-
-#include <stddef.h>
-
-#include <memory>
-#include <string>
-#include <vector>
-
-#include "base/callback.h"
-#include "base/macros.h"
-#include "base/memory/weak_ptr.h"
-
-namespace content {
-class BrowserContext;
-}
-
-namespace base {
-class FilePath;
-}  // namespace base
-
-namespace storage {
-class FileSystemURL;
-}  // namespace storage
-
-namespace extensions {
-namespace app_file_handler_util {
-
-// Gets a MIME type for a local path and returns it with |callback|. If not
-// found, then the MIME type is an empty string.
-void GetMimeTypeForLocalPath(
-    content::BrowserContext* context,
-    const base::FilePath& local_path,
-    const base::Callback<void(const std::string&)>& callback);
-
-// Collects MIME types for files passed in the input vector. For non-native
-// file systems tries to fetch the MIME type from metadata. For native ones,
-// tries to sniff or guess by looking at the extension. If MIME type is not
-// available, then an empty string is returned in the result vector.
-class MimeTypeCollector {
- public:
-  typedef base::Callback<void(std::unique_ptr<std::vector<std::string>>)>
-      CompletionCallback;
-
-  explicit MimeTypeCollector(content::BrowserContext* context);
-  virtual ~MimeTypeCollector();
-
-  // Collects all mime types asynchronously for a vector of URLs and upon
-  // completion, calls the |callback|. It can be called only once.
-  void CollectForURLs(const std::vector<storage::FileSystemURL>& urls,
-                      const CompletionCallback& callback);
-
-  // Collects all mime types asynchronously for a vector of local file paths and
-  // upon completion, calls the |callback|. It can be called only once.
-  void CollectForLocalPaths(const std::vector<base::FilePath>& local_paths,
-                            const CompletionCallback& callback);
-
- private:
-  // Called, when the |index|-th input file (or URL) got processed.
-  void OnMimeTypeCollected(size_t index, const std::string& mime_type);
-
-  content::BrowserContext* context_;
-  std::unique_ptr<std::vector<std::string>> result_;
-  size_t left_;
-  CompletionCallback callback_;
-  base::WeakPtrFactory<MimeTypeCollector> weak_ptr_factory_;
-
-  DISALLOW_COPY_AND_ASSIGN(MimeTypeCollector);
-};
-
-}  // namespace app_file_handler_util
-}  // namespace extensions
-
-#endif  // EXTENSIONS_BROWSER_API_FILE_HANDLERS_MIME_UTIL_H_