[FileAPI] Add file open ID and close callback

webkit/fileapi/file_system_operation.h

Index: webkit/fileapi/file_system_operation.h
diff --git a/webkit/fileapi/file_system_operation.h b/webkit/fileapi/file_system_operation.h
index c2e8fa587b5503f95e1f3c2f88319262588b52dc..15dd5972eff24d2f3411e9716bea6c2d8485b4a5 100644
--- a/webkit/fileapi/file_system_operation.h
+++ b/webkit/fileapi/file_system_operation.h
@@ -67,9 +67,12 @@ class FileSystemOperation {
            const base::FilePath& platform_path)> GetMetadataCallback;
 
   // Used for OpenFile(). |result| is the return code of the operation.
+  // |on_close_callback| will be called after the file is closed in the child
+  // process.
   typedef base::Callback<
       void(base::PlatformFileError result,
            base::PlatformFile file,
+           const base::Closure& on_close_callback,
            base::ProcessHandle peer_handle)> OpenFileCallback;
 
   // Used for ReadDirectoryCallback.