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

chrome/browser/extensions/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 CHROME_BROWSER_EXTENSIONS_API_FILE_HANDLERS_MIME_UTIL_H_
+#define CHROME_BROWSER_EXTENSIONS_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"
+
+class Profile;
+
+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(
+    Profile* profile,
+    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(Profile* profile);
+  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);
+
+  Profile* profile_;
+  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  // CHROME_BROWSER_EXTENSIONS_API_FILE_HANDLERS_MIME_UTIL_H_