Implement a poor man's PostAfterStartupTask() function.

content/browser/after_startup_task_poster_impl.cc

+// Copyright (c) 2015 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/after_startup_task_poster_impl.h"
+#include "base/task_runner.h"
+
+namespace content {
+
+namespace {
+
+AfterStartupTaskPoster* g_task_poster = nullptr;
+
+}
+
+void DefaultAfterStartupTaskPoster::PostAfterStartup(
+    const tracked_objects::Location& from_here,
+    const scoped_refptr<base::TaskRunner>& task_runner,
+    const base::Closure& task) {
+  task_runner->PostTask(from_here, task);
+}
+
+void DefaultAfterStartupTaskPoster::PostAfterStartupAndReply(
+    const tracked_objects::Location& from_here,
+    const scoped_refptr<base::TaskRunner>& task_runner,
+    const base::Closure& task,
+    const base::Closure& reply) {
+  task_runner->PostTaskAndReply(from_here, task, reply);
+}
+
+AfterStartupTaskPoster& GetAfterStartupTaskPoster() {
+  DCHECK(g_task_poster) ;
+  return *g_task_poster;
+}
+
+void SetAfterStartupTaskPoster(AfterStartupTaskPoster* task_poster) {
+  DCHECK(task_poster);
+  DCHECK(!g_task_poster);
+  g_task_poster = task_poster;
+}
+
+}  // namespace content