diff -r 000000000000 -r 6474c204b198 gfx/thebes/gfxQuartzImageSurface.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/thebes/gfxQuartzImageSurface.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,74 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * 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 "gfxQuartzImageSurface.h"
+#include "gfxImageSurface.h"
+
+#include "cairo-quartz-image.h"
+
+gfxQuartzImageSurface::gfxQuartzImageSurface(gfxImageSurface *imageSurface)
+{
+    if (imageSurface->CairoSurface() == nullptr)
+        return;
+
+    cairo_surface_t *surf = cairo_quartz_image_surface_create (imageSurface->CairoSurface());
+    Init (surf);
+    mSize = ComputeSize();
+}
+
+gfxQuartzImageSurface::gfxQuartzImageSurface(cairo_surface_t *csurf)
+{
+    Init (csurf, true);
+    mSize = ComputeSize();
+}
+
+gfxQuartzImageSurface::~gfxQuartzImageSurface()
+{
+}
+
+gfxIntSize
+gfxQuartzImageSurface::ComputeSize()
+{
+  if (mSurfaceValid) {
+    cairo_surface_t* isurf = cairo_quartz_image_surface_get_image(mSurface);
+    if (isurf) {
+      return gfxIntSize(cairo_image_surface_get_width(isurf),
+                        cairo_image_surface_get_height(isurf));
+    }
+  }
+
+  // If we reach here then something went wrong. Just use the same default
+  // value as gfxASurface::GetSize.
+  return gfxIntSize(-1, -1);
+}
+
+int32_t
+gfxQuartzImageSurface::KnownMemoryUsed()
+{
+  // This surface doesn't own any memory itself, but we want to report here the
+  // amount of memory that the surface it wraps uses.
+  nsRefPtr<gfxImageSurface> imgSurface = GetAsImageSurface();
+  if (imgSurface)
+    return imgSurface->KnownMemoryUsed();
+  return 0;
+}
+
+already_AddRefed<gfxImageSurface>
+gfxQuartzImageSurface::GetAsImageSurface()
+{
+    if (!mSurfaceValid)
+        return nullptr;
+
+    cairo_surface_t *isurf = cairo_quartz_image_surface_get_image (CairoSurface());
+    if (!isurf) {
+        NS_WARNING ("Couldn't obtain an image surface from a QuartzImageSurface?!");
+        return nullptr;
+    }
+
+    nsRefPtr<gfxImageSurface> result = gfxASurface::Wrap(isurf).downcast<gfxImageSurface>();
+    result->SetOpaqueRect(GetOpaqueRect());
+
+    return result.forget();
+}