Allow overlapping sync and async startup requests

content/browser/startup_task_runner.h

 // Copyright 2013 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.
 
 #ifndef CONTENT_BROWSER_STARTUP_TASK_RUNNER_H_
 #define CONTENT_BROWSER_STARTUP_TASK_RUNNER_H_
 
 #include <list>
 
 #include "base/callback.h"
-#include "base/memory/ref_counted.h"
 #include "base/single_thread_task_runner.h"
 
 #include "build/build_config.h"
 
 #include "content/public/browser/browser_main_runner.h"
 
 namespace content {
 
 // A startup task is a void function returning the status on completion.
 // a status of > 0 indicates a failure, and that no further startup tasks should
 // be run.
 typedef base::Callback<int(void)> StartupTask;
 
 // This class runs startup tasks. The tasks are either run immediately inline,
 // or are queued one at a time on the UI thread's message loop. If the events
 // are queued, UI events that are received during startup will be acted upon
 // between startup tasks. The motivation for this is that, on targets where the
 // UI is already started, it allows us to keep the UI responsive during startup.
 //
 // Note that this differs from a SingleThreadedTaskRunner in that there may be
 // no opportunity to handle UI events between the tasks of a
 // SingleThreadedTaskRunner.
 
-class CONTENT_EXPORT StartupTaskRunner
-    : public base::RefCounted<StartupTaskRunner> {
+class CONTENT_EXPORT StartupTaskRunner {
 
  public:
   // Constructor: Note that |startup_complete_callback| is optional. If it is
   // not null it will be called once all the startup tasks have run.
-  StartupTaskRunner(bool browser_may_start_asynchronously,
-                    base::Callback<void(int)> startup_complete_callback,
+  StartupTaskRunner(base::Callback<void(int)> startup_complete_callback,
                     scoped_refptr<base::SingleThreadTaskRunner> proxy);
 
+  ~StartupTaskRunner();
+
   // Add a task to the queue of startup tasks to be run.
-  virtual void AddTask(StartupTask& callback);
+  void AddTask(StartupTask& callback);
 
-  // Start running the tasks.
-  virtual void StartRunningTasks();
+  // Start running the tasks asynchronously.
+  void StartRunningTasksAsync();
+
+  // Run all tasks, or all remaining tasks, synchronously
+  void RunAllTasksNow();
 
  private:
   friend class base::RefCounted<StartupTaskRunner>;
-  virtual ~StartupTaskRunner();
 
   std::list<StartupTask> task_list_;
   void WrappedTask();
 
-  const bool asynchronous_startup_;
   base::Callback<void(int)> startup_complete_callback_;
   scoped_refptr<base::SingleThreadTaskRunner> proxy_;
 
   DISALLOW_COPY_AND_ASSIGN(StartupTaskRunner);
 };
 
 }  // namespace content
 #endif  // CONTENT_BROWSER_STARTUP_TASK_RUNNER_H_