diff -r 000000000000 -r 6474c204b198 dom/interfaces/base/nsICompositionStringSynthesizer.idl
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/interfaces/base/nsICompositionStringSynthesizer.idl	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,53 @@
+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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 obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ * Stores composition clauses information and caret information for synthesizing
+ * composition string.
+ */
+
+[scriptable, uuid(9a7d7851-8c0a-4061-9edc-60d6693f86c9)]
+interface nsICompositionStringSynthesizer : nsISupports
+{
+  /**
+   * Set composition string or committed string.
+   */
+  void setString(in AString aString);
+
+  // NOTE: These values must be same to NS_TEXTRANGE_* in TextEvents.h
+  const unsigned long ATTR_RAWINPUT              = 0x02;
+  const unsigned long ATTR_SELECTEDRAWTEXT       = 0x03;
+  const unsigned long ATTR_CONVERTEDTEXT         = 0x04;
+  const unsigned long ATTR_SELECTEDCONVERTEDTEXT = 0x05;
+
+  /**
+   * Append a clause.
+   *
+   * TODO: Should be able to specify custom clause style.
+   */
+  void appendClause(in unsigned long aLength,
+                    in unsigned long aAttribute);
+
+  /**
+   * Set caret information.
+   */
+  void setCaret(in unsigned long aOffset,
+                in unsigned long aLength);
+
+  /**
+   * Synthesize composition string with given information by dispatching
+   * a proper event.
+   *
+   * If clauses have never been set, this dispatches a commit event.
+   * If clauses are not filled all over the composition string, this throw an
+   * error.
+   *
+   * After dispatching event, this clears all the information about the
+   * composition string. So, you can reuse this instance.
+   */
+  bool dispatchEvent();
+};