diff -r 000000000000 -r 6474c204b198 dom/base/nsStructuredCloneContainer.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/base/nsStructuredCloneContainer.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,170 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sw=2 et tw=80:
+ *
+ * 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 "nsStructuredCloneContainer.h"
+
+#include "nsCOMPtr.h"
+#include "nsIScriptContext.h"
+#include "nsIVariant.h"
+#include "nsIXPConnect.h"
+#include "nsServiceManagerUtils.h"
+#include "nsContentUtils.h"
+#include "jsapi.h"
+#include "js/StructuredClone.h"
+
+#include "mozilla/Base64.h"
+
+using namespace mozilla;
+
+NS_IMPL_ADDREF(nsStructuredCloneContainer)
+NS_IMPL_RELEASE(nsStructuredCloneContainer)
+
+NS_INTERFACE_MAP_BEGIN(nsStructuredCloneContainer)
+  NS_INTERFACE_MAP_ENTRY(nsIStructuredCloneContainer)
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+nsStructuredCloneContainer::nsStructuredCloneContainer()
+  : mData(nullptr), mSize(0), mVersion(0)
+{
+}
+
+nsStructuredCloneContainer::~nsStructuredCloneContainer()
+{
+  free(mData);
+}
+
+nsresult
+nsStructuredCloneContainer::InitFromJSVal(JS::Handle<JS::Value> aData,
+                                          JSContext* aCx)
+{
+  NS_ENSURE_STATE(!mData);
+  NS_ENSURE_ARG_POINTER(aCx);
+
+  // Make sure that we serialize in the right context.
+  MOZ_ASSERT(aCx == nsContentUtils::GetCurrentJSContext());
+  JS::Rooted<JS::Value> jsData(aCx, aData);
+  bool success = JS_WrapValue(aCx, &jsData);
+  NS_ENSURE_STATE(success);
+
+  uint64_t* jsBytes = nullptr;
+  success = JS_WriteStructuredClone(aCx, jsData, &jsBytes, &mSize,
+                                    nullptr, nullptr,
+                                    JS::UndefinedHandleValue);
+  NS_ENSURE_STATE(success);
+  NS_ENSURE_STATE(jsBytes);
+
+  // Copy jsBytes into our own buffer.
+  mData = (uint64_t*) malloc(mSize);
+  if (!mData) {
+    mSize = 0;
+    mVersion = 0;
+
+    JS_ClearStructuredClone(jsBytes, mSize, nullptr, nullptr);
+    return NS_ERROR_FAILURE;
+  }
+  else {
+    mVersion = JS_STRUCTURED_CLONE_VERSION;
+  }
+
+  memcpy(mData, jsBytes, mSize);
+
+  JS_ClearStructuredClone(jsBytes, mSize, nullptr, nullptr);
+  return NS_OK;
+}
+
+nsresult
+nsStructuredCloneContainer::InitFromBase64(const nsAString &aData,
+                                           uint32_t aFormatVersion,
+                                           JSContext *aCx)
+{
+  NS_ENSURE_STATE(!mData);
+
+  NS_ConvertUTF16toUTF8 data(aData);
+
+  nsAutoCString binaryData;
+  nsresult rv = Base64Decode(data, binaryData);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // Copy the string's data into our own buffer.
+  mData = (uint64_t*) malloc(binaryData.Length());
+  NS_ENSURE_STATE(mData);
+  memcpy(mData, binaryData.get(), binaryData.Length());
+
+  mSize = binaryData.Length();
+  mVersion = aFormatVersion;
+  return NS_OK;
+}
+
+
+nsresult
+nsStructuredCloneContainer::DeserializeToVariant(JSContext *aCx,
+                                                 nsIVariant **aData)
+{
+  NS_ENSURE_STATE(mData);
+  NS_ENSURE_ARG_POINTER(aData);
+  *aData = nullptr;
+
+  // Deserialize to a JS::Value.
+  JS::Rooted<JS::Value> jsStateObj(aCx);
+  bool hasTransferable = false;
+  bool success = JS_ReadStructuredClone(aCx, mData, mSize, mVersion,
+                                        &jsStateObj, nullptr, nullptr) &&
+                 JS_StructuredCloneHasTransferables(mData, mSize,
+                                                    &hasTransferable);
+  // We want to be sure that mData doesn't contain transferable objects
+  MOZ_ASSERT(!hasTransferable);
+  NS_ENSURE_STATE(success && !hasTransferable);
+
+  // Now wrap the JS::Value as an nsIVariant.
+  nsCOMPtr<nsIVariant> varStateObj;
+  nsCOMPtr<nsIXPConnect> xpconnect = do_GetService(nsIXPConnect::GetCID());
+  NS_ENSURE_STATE(xpconnect);
+  xpconnect->JSValToVariant(aCx, jsStateObj, getter_AddRefs(varStateObj));
+  NS_ENSURE_STATE(varStateObj);
+
+  NS_ADDREF(*aData = varStateObj);
+  return NS_OK;
+}
+
+nsresult
+nsStructuredCloneContainer::GetDataAsBase64(nsAString &aOut)
+{
+  NS_ENSURE_STATE(mData);
+  aOut.Truncate();
+
+  nsAutoCString binaryData(reinterpret_cast<char*>(mData), mSize);
+  nsAutoCString base64Data;
+  nsresult rv = Base64Encode(binaryData, base64Data);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  aOut.Assign(NS_ConvertASCIItoUTF16(base64Data));
+  return NS_OK;
+}
+
+nsresult
+nsStructuredCloneContainer::GetSerializedNBytes(uint64_t *aSize)
+{
+  NS_ENSURE_STATE(mData);
+  NS_ENSURE_ARG_POINTER(aSize);
+
+  // mSize is a size_t, while aSize is a uint64_t.  We rely on an implicit cast
+  // here so that we'll get a compile error if a size_t-to-uint64_t cast is
+  // narrowing.
+  *aSize = mSize;
+
+  return NS_OK;
+}
+
+nsresult
+nsStructuredCloneContainer::GetFormatVersion(uint32_t *aFormatVersion)
+{
+  NS_ENSURE_STATE(mData);
+  NS_ENSURE_ARG_POINTER(aFormatVersion);
+  *aFormatVersion = mVersion;
+  return NS_OK;
+}