diff -r 000000000000 -r 6474c204b198 dom/webidl/LockedFile.webidl
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/webidl/LockedFile.webidl	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,48 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtaone at http://mozilla.org/MPL/2.0/. */
+
+dictionary DOMFileMetadataParameters
+{
+  boolean size = true;
+  boolean lastModified = true;
+};
+
+interface LockedFile : EventTarget
+{
+  readonly attribute FileHandle? fileHandle;
+  readonly attribute FileMode mode;
+  readonly attribute boolean active;
+  attribute unsigned long long? location;
+
+  [Throws]
+  FileRequest? getMetadata(optional DOMFileMetadataParameters parameters);
+  [Throws]
+  FileRequest? readAsArrayBuffer(unsigned long long size);
+  [Throws]
+  FileRequest? readAsText(unsigned long long size,
+                         optional DOMString? encoding = null);
+
+  [Throws]
+  FileRequest? write(ArrayBuffer value);
+  [Throws]
+  FileRequest? write(Blob value);
+  [Throws]
+  FileRequest? write(DOMString value);
+  [Throws]
+  FileRequest? append(ArrayBuffer value);
+  [Throws]
+  FileRequest? append(Blob value);
+  [Throws]
+  FileRequest? append(DOMString value);
+  [Throws]
+  FileRequest? truncate(optional unsigned long long size);
+  [Throws]
+  FileRequest? flush();
+  [Throws]
+  void abort();
+
+  attribute EventHandler oncomplete;
+  attribute EventHandler onabort;
+  attribute EventHandler onerror;
+};