(For-try) Divide recursive Copy/Move into multiple async tasks

webkit/fileapi/file_system_file_util.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 WEBKIT_FILEAPI_FILE_SYSTEM_FILE_UTIL_H_
 #define WEBKIT_FILEAPI_FILE_SYSTEM_FILE_UTIL_H_
 
 #include "base/file_path.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/platform_file.h"
@@ skipping 137 matching lines @@
       const base::Time& last_access_time,
       const base::Time& last_modified_time) = 0;
 
   // Truncates a file to the given length.  If |length| is greater than the
   // current length of the file, the file will be extended with zeroes.
   virtual base::PlatformFileError Truncate(
       FileSystemOperationContext* context,
       const FileSystemURL& url,
       int64 length) = 0;
 
-  // Returns true if a given |url| is an empty directory.
-  virtual bool IsDirectoryEmpty(
-      FileSystemOperationContext* context,
-      const FileSystemURL& url) = 0;
-
   // Copies or moves a single file from |src_url| to |dest_url|.
+  // The filesystem type of |src_url| and |dest_url| MUST be same.
+  //
+  // This returns:
+  // - PLATFORM_FILE_ERROR_NOT_FOUND if |src_url|
+  //   or the parent directory of |dest_url| does not exist.
+  // - PLATFORM_FILE_ERROR_NOT_A_FILE if |src_url| exists but is not a file.
+  // - PLATFORM_FILE_ERROR_INVALID_OPERATION if |dest_url| exists and
+  //   is not a file.
+  // - PLATFORM_FILE_ERROR_FAILED if |dest_url| does not exist and
+  //   its parent path is a file.
+  //
   virtual base::PlatformFileError CopyOrMoveFile(
       FileSystemOperationContext* context,
       const FileSystemURL& src_url,
       const FileSystemURL& dest_url,
       bool copy) = 0;
 
   // Copies in a single file from a different filesystem.
+  //
+  // This returns:
+  // - PLATFORM_FILE_ERROR_NOT_FOUND if |src_file_path|
+  //   or the parent directory of |dest_url| does not exist.
+  // - PLATFORM_FILE_ERROR_INVALID_OPERATION if |dest_url| exists and
+  //   is not a file.
+  // - PLATFORM_FILE_ERROR_FAILED if |dest_url| does not exist and
+  //   its parent path is a file.
+  //
   virtual base::PlatformFileError CopyInForeignFile(
         FileSystemOperationContext* context,
         const FilePath& src_file_path,
         const FileSystemURL& dest_url) = 0;
 
   // Deletes a single file.
-  // It assumes the given url points a file.
+  //
+  // This returns:
+  // - PLATFORM_FILE_ERROR_NOT_FOUND if |url| does not exist.
+  // - PLATFORM_FILE_ERROR_NOT_A_FILE if |url| is not a file.
+  //
   virtual base::PlatformFileError DeleteFile(
       FileSystemOperationContext* context,
       const FileSystemURL& url) = 0;
 
   // Deletes a single empty directory.
-  // It assumes the given url points an empty directory.
-  virtual base::PlatformFileError DeleteSingleDirectory(
+  //
+  // This returns:
+  // - PLATFORM_FILE_ERROR_NOT_FOUND if |url| does not exist.
+  // - PLATFORM_FILE_ERROR_NOT_A_DIRECTORY if |url| is not a directory.
+  // - PLATFORM_FILE_ERROR_NOT_EMPTY if |url| is not empty.
+  //
+  virtual base::PlatformFileError DeleteDirectory(
       FileSystemOperationContext* context,
       const FileSystemURL& url) = 0;
 
   // Creates a local snapshot file for a given |url| and returns the
   // metadata and platform path of the snapshot file via |callback|.
   // In regular filesystem cases the implementation may simply return
   // the metadata of the file itself (as well as GetMetadata does),
   // while in non-regular filesystem case the backend may create a
   // temporary snapshot file which holds the file data and return
   // the metadata of the temporary file.
   //
   // |file_info| is the metadata of the snapshot file created.
   // |platform_path| is the path to the snapshot file created.
   // |policy| should indicate the policy how the fileapi backend
   // should handle the returned file.
+  //
+  // This returns:
+  // - PLATFORM_FILE_ERROR_NOT_FOUND if |url| does not exist.
+  // - PLATFORM_FILE_ERROR_NOT_A_FILE if |url| is not a file.
+  //
   virtual base::PlatformFileError CreateSnapshotFile(
       FileSystemOperationContext* context,
       const FileSystemURL& url,
       base::PlatformFileInfo* file_info,
       FilePath* platform_path,
       SnapshotFilePolicy* policy) = 0;
 
  protected:
   FileSystemFileUtil() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FileSystemFileUtil);
 };
 
 }  // namespace fileapi
 
 #endif  // WEBKIT_FILEAPI_FILE_SYSTEM_FILE_UTIL_H_