diff -r 000000000000 -r 6474c204b198 image/src/ImageURL.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/image/src/ImageURL.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,93 @@
+/* -*- 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 MOZILLA_IMAGELIB_IMAGEURL_H_
+#define MOZILLA_IMAGELIB_IMAGEURL_H_
+
+#include "nsIURI.h"
+#include "MainThreadUtils.h"
+#include "nsNetUtil.h"
+
+namespace mozilla {
+namespace image {
+
+/** ImageURL
+ *
+ * nsStandardURL is not threadsafe, so this class is created to hold only the
+ * necessary URL data required for image loading and decoding.
+ *
+ * Note: Although several APIs have the same or similar prototypes as those
+ * found in nsIURI/nsStandardURL, the class does not implement nsIURI. This is
+ * intentional; functionality is limited, and is only useful for imagelib code.
+ * By not implementing nsIURI, external code cannot unintentionally be given an
+ * nsIURI pointer with this limited class behind it; instead, conversion to a
+ * fully implemented nsIURI is required (e.g. through NS_NewURI).
+ */
+class ImageURL
+{
+public:
+  explicit ImageURL(nsIURI* aURI) {
+    MOZ_ASSERT(NS_IsMainThread(), "Cannot use nsIURI off main thread!");
+    aURI->GetSpec(mSpec);
+    aURI->GetScheme(mScheme);
+    aURI->GetRef(mRef);
+  }
+
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(mozilla::image::ImageURL)
+
+  nsresult GetSpec(nsACString &result) {
+    result = mSpec;
+    return NS_OK;
+  }
+
+  nsresult GetScheme(nsACString &result) {
+    result = mScheme;
+    return NS_OK;
+  }
+
+  nsresult SchemeIs(const char *scheme, bool *result)
+  {
+    NS_PRECONDITION(scheme, "scheme is null");
+    NS_PRECONDITION(result, "result is null");
+
+    *result = mScheme.Equals(scheme);
+    return NS_OK;
+  }
+
+  nsresult GetRef(nsACString &result) {
+    result = mRef;
+    return NS_OK;
+  }
+
+  already_AddRefed<nsIURI> ToIURI() {
+    MOZ_ASSERT(NS_IsMainThread(),
+               "Convert to nsIURI on main thread only; it is not threadsafe.");
+    nsCOMPtr<nsIURI> newURI;
+    NS_NewURI(getter_AddRefs(newURI), mSpec);
+    return newURI.forget();
+  }
+
+  nsresult Equals(nsIURI *otherURI, bool *result) {
+    nsAutoCString otherSpec;    
+    otherURI->GetSpec(otherSpec);
+    *result = mSpec.Equals(otherSpec);
+    return NS_OK;
+  }
+
+private:
+  // Since this is a basic storage class, no duplication of spec parsing is
+  // included in the functionality. Instead, the class depends upon the
+  // parsing implementation in the nsIURI class used in object construction.
+  // This means each field is stored separately, but since only a few are
+  // required, this small memory tradeoff for threadsafe usage should be ok.
+  nsAutoCString mSpec;
+  nsAutoCString mScheme;
+  nsAutoCString mRef;
+};
+
+} // namespace image
+} // namespace mozilla
+
+#endif // MOZILLA_IMAGELIB_IMAGEURL_H_