diff -r 000000000000 -r 6474c204b198 widget/xpwidgets/GfxInfoWebGL.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/widget/xpwidgets/GfxInfoWebGL.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,69 @@
+/* vim: se cin sw=2 ts=2 et : */
+/* -*- Mode: C++; 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 "GfxInfoWebGL.h"
+
+#include "nsServiceManagerUtils.h"
+
+#include "GLDefs.h"
+#include "nsIDOMWebGLRenderingContext.h"
+#include "nsICanvasRenderingContextInternal.h"
+
+using namespace mozilla::widget;
+
+nsresult
+GfxInfoWebGL::GetWebGLParameter(const nsAString& aParam, nsAString& aResult)
+{
+  GLenum param;
+
+  if (aParam.EqualsLiteral("vendor")) param = LOCAL_GL_VENDOR;
+  else if (aParam.EqualsLiteral("renderer")) param = LOCAL_GL_RENDERER;
+  else if (aParam.EqualsLiteral("version")) param = LOCAL_GL_VERSION;
+  else if (aParam.EqualsLiteral("shading_language_version")) param = LOCAL_GL_SHADING_LANGUAGE_VERSION;
+  else if (aParam.EqualsLiteral("extensions")) param = LOCAL_GL_EXTENSIONS;
+  else if (aParam.EqualsLiteral("full-renderer")) param = 0;
+  else return NS_ERROR_INVALID_ARG;
+
+  nsCOMPtr<nsIDOMWebGLRenderingContext> webgl =
+    do_CreateInstance("@mozilla.org/content/canvas-rendering-context;1?id=experimental-webgl");
+  if (!webgl)
+    return NS_ERROR_NOT_AVAILABLE;
+
+  nsCOMPtr<nsICanvasRenderingContextInternal> webglInternal =
+    do_QueryInterface(webgl);
+  if (!webglInternal)
+    return NS_ERROR_NOT_AVAILABLE;
+
+  nsresult rv = webglInternal->SetDimensions(16, 16);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (param)
+    return webgl->MozGetUnderlyingParamString(param, aResult);
+
+  // this is the "full renderer" string, which is vendor + renderer + version
+
+  nsAutoString str;
+
+  rv = webgl->MozGetUnderlyingParamString(LOCAL_GL_VENDOR, str);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  aResult.Append(str);
+  aResult.AppendLiteral(" -- ");
+
+  rv = webgl->MozGetUnderlyingParamString(LOCAL_GL_RENDERER, str);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  aResult.Append(str);
+  aResult.AppendLiteral(" -- ");
+
+  rv = webgl->MozGetUnderlyingParamString(LOCAL_GL_VERSION, str);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  aResult.Append(str);
+
+  return NS_OK;
+}