diff -r 000000000000 -r 6474c204b198 gfx/src/X11Util.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/src/X11Util.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,86 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: sw=2 ts=8 et :
+ */
+/* 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 "X11Util.h"
+#include "nsDebug.h"                    // for NS_ASSERTION, etc
+
+namespace mozilla {
+
+void
+FindVisualAndDepth(Display* aDisplay, VisualID aVisualID,
+                   Visual** aVisual, int* aDepth)
+{
+    const Screen* screen = DefaultScreenOfDisplay(aDisplay);
+
+    for (int d = 0; d < screen->ndepths; d++) {
+        Depth *d_info = &screen->depths[d];
+        for (int v = 0; v < d_info->nvisuals; v++) {
+            Visual* visual = &d_info->visuals[v];
+            if (visual->visualid == aVisualID) {
+                *aVisual = visual;
+                *aDepth = d_info->depth;
+                return;
+            }
+        }
+    }
+
+    NS_ASSERTION(aVisualID == None, "VisualID not on Screen.");
+    *aVisual = nullptr;
+    *aDepth = 0;
+    return;
+}
+
+void
+FinishX(Display* aDisplay)
+{
+  unsigned long lastRequest = NextRequest(aDisplay) - 1;
+  if (lastRequest == LastKnownRequestProcessed(aDisplay))
+    return;
+
+  XSync(aDisplay, False);
+}
+
+ScopedXErrorHandler::ErrorEvent* ScopedXErrorHandler::sXErrorPtr;
+
+int
+ScopedXErrorHandler::ErrorHandler(Display *, XErrorEvent *ev)
+{
+    // only record the error if no error was previously recorded.
+    // this means that in case of multiple errors, it's the first error that we report.
+    if (!sXErrorPtr->mError.error_code)
+      sXErrorPtr->mError = *ev;
+    return 0;
+}
+
+ScopedXErrorHandler::ScopedXErrorHandler()
+{
+    // let sXErrorPtr point to this object's mXError object, but don't reset this mXError object!
+    // think of the case of nested ScopedXErrorHandler's.
+    mOldXErrorPtr = sXErrorPtr;
+    sXErrorPtr = &mXError;
+    mOldErrorHandler = XSetErrorHandler(ErrorHandler);
+}
+
+ScopedXErrorHandler::~ScopedXErrorHandler()
+{
+    sXErrorPtr = mOldXErrorPtr;
+    XSetErrorHandler(mOldErrorHandler);
+}
+
+bool
+ScopedXErrorHandler::SyncAndGetError(Display *dpy, XErrorEvent *ev)
+{
+    FinishX(dpy);
+
+    bool retval = mXError.mError.error_code != 0;
+    if (ev)
+        *ev = mXError.mError;
+    mXError = ErrorEvent(); // reset
+    return retval;
+}
+
+} // namespace mozilla