diff -r 000000000000 -r 6474c204b198 storage/src/mozStorageAsyncStatementJSHelper.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/storage/src/mozStorageAsyncStatementJSHelper.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,116 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
+ * 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 "nsIXPConnect.h"
+#include "mozStorageAsyncStatement.h"
+#include "mozStorageService.h"
+
+#include "nsMemory.h"
+#include "nsString.h"
+#include "nsServiceManagerUtils.h"
+
+#include "mozStorageAsyncStatementJSHelper.h"
+
+#include "mozStorageAsyncStatementParams.h"
+
+#include "jsapi.h"
+
+namespace mozilla {
+namespace storage {
+
+////////////////////////////////////////////////////////////////////////////////
+//// AsyncStatementJSHelper
+
+nsresult
+AsyncStatementJSHelper::getParams(AsyncStatement *aStatement,
+                                  JSContext *aCtx,
+                                  JSObject *aScopeObj,
+                                  jsval *_params)
+{
+  nsresult rv;
+
+#ifdef DEBUG
+  int32_t state;
+  (void)aStatement->GetState(&state);
+  NS_ASSERTION(state == mozIStorageAsyncStatement::MOZ_STORAGE_STATEMENT_READY,
+               "Invalid state to get the params object - all calls will fail!");
+#endif
+
+  if (!aStatement->mStatementParamsHolder) {
+    nsCOMPtr<mozIStorageStatementParams> params =
+      new AsyncStatementParams(aStatement);
+    NS_ENSURE_TRUE(params, NS_ERROR_OUT_OF_MEMORY);
+
+    JS::RootedObject scope(aCtx, aScopeObj);
+    nsCOMPtr<nsIXPConnect> xpc(Service::getXPConnect());
+    rv = xpc->WrapNative(
+      aCtx,
+      ::JS_GetGlobalForObject(aCtx, scope),
+      params,
+      NS_GET_IID(mozIStorageStatementParams),
+      getter_AddRefs(aStatement->mStatementParamsHolder)
+    );
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  JS::Rooted<JSObject*> obj(aCtx);
+  obj = aStatement->mStatementParamsHolder->GetJSObject();
+  NS_ENSURE_STATE(obj);
+
+  *_params = OBJECT_TO_JSVAL(obj);
+  return NS_OK;
+}
+
+NS_IMETHODIMP_(MozExternalRefCountType) AsyncStatementJSHelper::AddRef() { return 2; }
+NS_IMETHODIMP_(MozExternalRefCountType) AsyncStatementJSHelper::Release() { return 1; }
+NS_INTERFACE_MAP_BEGIN(AsyncStatementJSHelper)
+  NS_INTERFACE_MAP_ENTRY(nsIXPCScriptable)
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+////////////////////////////////////////////////////////////////////////////////
+//// nsIXPCScriptable
+
+#define XPC_MAP_CLASSNAME AsyncStatementJSHelper
+#define XPC_MAP_QUOTED_CLASSNAME "AsyncStatementJSHelper"
+#define XPC_MAP_WANT_GETPROPERTY
+#define XPC_MAP_FLAGS nsIXPCScriptable::ALLOW_PROP_MODS_DURING_RESOLVE
+#include "xpc_map_end.h"
+
+NS_IMETHODIMP
+AsyncStatementJSHelper::GetProperty(nsIXPConnectWrappedNative *aWrapper,
+                                    JSContext *aCtx,
+                                    JSObject *aScopeObj,
+                                    jsid aId,
+                                    jsval *_result,
+                                    bool *_retval)
+{
+  if (!JSID_IS_STRING(aId))
+    return NS_OK;
+
+  // Cast to async via mozI* since direct from nsISupports is ambiguous.
+  JS::RootedObject scope(aCtx, aScopeObj);
+  JS::RootedId id(aCtx, aId);
+  mozIStorageAsyncStatement *iAsyncStmt =
+    static_cast<mozIStorageAsyncStatement *>(aWrapper->Native());
+  AsyncStatement *stmt = static_cast<AsyncStatement *>(iAsyncStmt);
+
+#ifdef DEBUG
+  {
+    nsISupports *supp = aWrapper->Native();
+    nsCOMPtr<mozIStorageAsyncStatement> isStatement(do_QueryInterface(supp));
+    NS_ASSERTION(isStatement, "How is this not an async statement?!");
+  }
+#endif
+
+  if (::JS_FlatStringEqualsAscii(JSID_TO_FLAT_STRING(id), "params"))
+    return getParams(stmt, aCtx, scope, _result);
+
+  return NS_OK;
+}
+
+} // namespace storage
+} // namespace mozilla