diff -r 000000000000 -r 6474c204b198 content/canvas/src/CanvasImageCache.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/content/canvas/src/CanvasImageCache.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,51 @@
+/* -*- 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/. */
+
+#ifndef CANVASIMAGECACHE_H_
+#define CANVASIMAGECACHE_H_
+
+#include "nsSize.h"
+
+namespace mozilla {
+namespace dom {
+class Element;
+class HTMLCanvasElement;
+} // namespace dom
+namespace gfx {
+class SourceSurface;
+} // namespace gfx
+} // namespace mozilla
+class imgIRequest;
+
+namespace mozilla {
+
+class CanvasImageCache {
+  typedef mozilla::gfx::SourceSurface SourceSurface;
+public:
+  /**
+   * Notify that image element aImage was (or is about to be) drawn to aCanvas
+   * using the first frame of aRequest's image. The data for the surface is
+   * in aSurface, and the image size is in aSize.
+   */
+  static void NotifyDrawImage(dom::Element* aImage,
+                              dom::HTMLCanvasElement* aCanvas,
+                              imgIRequest* aRequest,
+                              SourceSurface* aSource,
+                              const gfxIntSize& aSize);
+
+  /**
+   * Check whether aImage has recently been drawn into aCanvas. If we return
+   * a non-null surface, then the image was recently drawn into the canvas
+   * (with the same image request) and the returned surface contains the image
+   * data, and the image size will be returned in aSize.
+   */
+  static SourceSurface* Lookup(dom::Element* aImage,
+                               dom::HTMLCanvasElement* aCanvas,
+                               gfxIntSize* aSize);
+};
+
+}
+
+#endif /* CANVASIMAGECACHE_H_ */