drive: Enable a hook to update the default download directory.

chrome/browser/chromeos/drive/drive_file_system_util.cc

 // 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.
 
 #include "chrome/browser/chromeos/drive/drive_file_system_util.h"
 
 #include <string>
 #include <utility>
 #include <vector>
 
@@ skipping 214 matching lines @@
     *url = GURL();
   }
 }
 
 bool IsUnderDriveMountPoint(const base::FilePath& path) {
   return GetDriveMountPointPath() == path ||
          GetDriveMountPointPath().IsParent(path);
 }
 
 bool NeedsNamespaceMigration(const base::FilePath& path) {
-  return false;
-  // TODO(haruki): Update this along with http://crbug.com/174233.
-  //  return IsUnderDriveMountPoint(path) &&
-  //      !(GetDriveMyDriveMountPointPath() == path ||
-  //          GetDriveMyDriveMountPointPath().IsParent(path));
+  // Before migration, "My Drive" which was represented as "drive.
+  // The user might use some path pointing a directory in "My Drive".
+  // e.g. "drive/downloads_dir"
+  // We changed the path for the "My Drive" to "drive/root", hence the user pref
+  // pointing to the old path needs update to the new path.
+  // e.g. "drive/root/downloads_dir"
+  // If |path| already points to some directory in "drive/root", there's no need
+  // to update it.
+  return IsUnderDriveMountPoint(path) &&
+         !(GetDriveMyDriveMountPointPath() == path ||
+           GetDriveMyDriveMountPointPath().IsParent(path));
 }
 
 base::FilePath ConvertToMyDriveNamespace(const base::FilePath& path) {
-  // Double check the path.
-  // TODO(haruki): Update this with DCHECK(NeedsNamespaceMigration(path)).
-  DCHECK(IsUnderDriveMountPoint(path) &&
-         !(GetDriveMyDriveMountPointPath() == path ||
-           GetDriveMyDriveMountPointPath().IsParent(path)));
+  DCHECK(NeedsNamespaceMigration(path));
 
   // Need to migrate "/special/drive(.*)" to "/special/drive/root(.*)".
   // Append the relative path from "/special/drive".
   base::FilePath new_path(GetDriveMyDriveMountPointPath());
   GetDriveMountPointPath().AppendRelativePath(path, &new_path);
   DVLOG(1) << "Migrate download.default_directory setting from "
       << path.AsUTF8Unsafe() << " to " << new_path.AsUTF8Unsafe();
   DCHECK(!NeedsNamespaceMigration(new_path));
   return new_path;
 }
@@ skipping 172 matching lines @@
   proto->set_last_modified(file_info.last_modified.ToInternalValue());
   proto->set_last_accessed(file_info.last_accessed.ToInternalValue());
   proto->set_creation_time(file_info.creation_time.ToInternalValue());
 }
 
 void EmptyFileOperationCallback(DriveFileError error) {
 }
 
 }  // namespace util
 }  // namespace drive