diff -r 000000000000 -r 6474c204b198 accessible/src/xpcom/xpcAccessibleValue.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/accessible/src/xpcom/xpcAccessibleValue.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,90 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* 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 "xpcAccessibleValue.h"
+#include "Accessible.h"
+
+using namespace mozilla;
+using namespace mozilla::a11y;
+
+NS_IMETHODIMP
+xpcAccessibleValue::GetMaximumValue(double* aValue)
+{
+  NS_ENSURE_ARG_POINTER(aValue);
+  *aValue = 0;
+
+  Accessible* acc = static_cast<Accessible*>(this);
+  if (acc->IsDefunct())
+    return NS_ERROR_FAILURE;
+
+  double value = acc->MaxValue();
+  if (!IsNaN(value))
+    *aValue = value;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+xpcAccessibleValue::GetMinimumValue(double* aValue)
+{
+  NS_ENSURE_ARG_POINTER(aValue);
+  *aValue = 0;
+
+  Accessible* acc = static_cast<Accessible*>(this);
+  if (acc->IsDefunct())
+    return NS_ERROR_FAILURE;
+
+  double value = acc->MinValue();
+  if (!IsNaN(value))
+    *aValue = value;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+xpcAccessibleValue::GetCurrentValue(double* aValue)
+{
+  NS_ENSURE_ARG_POINTER(aValue);
+  *aValue = 0;
+
+  Accessible* acc = static_cast<Accessible*>(this);
+  if (acc->IsDefunct())
+    return NS_ERROR_FAILURE;
+
+  double value = acc->CurValue();
+  if (!IsNaN(value))
+    *aValue = value;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+xpcAccessibleValue::SetCurrentValue(double aValue)
+{
+  Accessible* acc = static_cast<Accessible*>(this);
+  if (acc->IsDefunct())
+    return NS_ERROR_FAILURE;
+
+  acc->SetCurValue(aValue);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+xpcAccessibleValue::GetMinimumIncrement(double* aValue)
+{
+  NS_ENSURE_ARG_POINTER(aValue);
+  *aValue = 0;
+
+  Accessible* acc = static_cast<Accessible*>(this);
+  if (acc->IsDefunct())
+    return NS_ERROR_FAILURE;
+
+  double value = acc->Step();
+  if (!IsNaN(value))
+    *aValue = value;
+
+  return NS_OK;
+}