[downloads] Move platform specific code out of DownloadTargetDeterminer.

chrome/browser/download/download_path_reservation_tracker.h

 // 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.
 
 #ifndef CHROME_BROWSER_DOWNLOAD_DOWNLOAD_PATH_RESERVATION_TRACKER_H_
 #define CHROME_BROWSER_DOWNLOAD_DOWNLOAD_PATH_RESERVATION_TRACKER_H_
 
 #include "base/callback_forward.h"
 
 namespace base {
 class FilePath;
 }
 
 namespace content {
 class DownloadItem;
 }
 
+enum class PathValidationResult {
+  SUCCESS,
+  PATH_NOT_WRITABLE,
+  NAME_TOO_LONG,
+  CONFLICT
+};
+
 // Chrome attempts to uniquify filenames that are assigned to downloads in order
 // to avoid overwriting files that already exist on the file system. Downloads
 // that are considered potentially dangerous use random intermediate filenames.
 // Therefore only considering files that exist on the filesystem is
 // insufficient. This class tracks files that are assigned to active downloads
 // so that uniquification can take those into account as well.
 class DownloadPathReservationTracker {
  public:
   // Callback used with |GetReservedPath|. |target_path| specifies the target
-  // path for the download. |target_path_verified| is true if all of the
-  // following is true:
+  // path for the download. If |result| is SUCCESS then:
   // - |requested_target_path| (passed into GetReservedPath()) was writeable.
   // - |target_path| was verified as being unique if uniqueness was
   //   required.
   //
   // If |requested_target_path| was not writeable, then the parent directory of
   // |target_path| may be different from that of |requested_target_path|.
-  typedef base::Callback<void(const base::FilePath& target_path,
-                              bool target_path_verified)> ReservedPathCallback;
+  using ReservedPathCallback =
+      base::Callback<void(PathValidationResult result,
+                          const base::FilePath& target_path)>;
 
   // The largest index for the uniquification suffix that we will try while
   // attempting to come up with a unique path.
   static const int kMaxUniqueFiles = 100;
 
   enum FilenameConflictAction {
     UNIQUIFY,
     OVERWRITE,
     PROMPT,
   };
@@ skipping 44 matching lines @@
       bool create_directory,
       FilenameConflictAction conflict_action,
       const ReservedPathCallback& callback);
 
   // Returns true if |path| is in use by an existing path reservation. Should
   // only be called on the FILE thread. Currently only used by tests.
   static bool IsPathInUseForTesting(const base::FilePath& path);
 };
 
 #endif  // CHROME_BROWSER_DOWNLOAD_DOWNLOAD_PATH_RESERVATION_TRACKER_H_