Fix history importing by delaying DownloadManager creation.

content/browser/download/download_id_factory.cc

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/browser/download/download_id_factory.h"
+
+#include "content/browser/download/download_id.h"
+
+DownloadIdFactory::DownloadIdFactory(DownloadId::Domain domain)
+  : domain_(domain),
+    next_id_(0) {
+}
+
+DownloadId DownloadIdFactory::GetNextId() {
+  base::AutoLock lock(lock_);
+  return DownloadId(domain_, next_id_++);
+}
+
+void DownloadIdFactory::SetNextId(int next_id) {
+  base::AutoLock lock(lock_);
+  next_id_ += next_id;
+}