Lazily initialize MessageLoop for faster thread startup

base/message_loop/incoming_task_queue.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 BASE_MESSAGE_LOOP_INCOMING_TASK_QUEUE_H_
 #define BASE_MESSAGE_LOOP_INCOMING_TASK_QUEUE_H_
 
 #include "base/base_export.h"
 #include "base/memory/ref_counted.h"
 #include "base/pending_task.h"
@@ skipping 35 matching lines @@
   bool IsIdleForTesting();
 
   // Loads tasks from the |incoming_queue_| into |*work_queue|. Must be called
   // from the thread that is running the loop. Returns the number of tasks that
   // require high resolution timers.
   int ReloadWorkQueue(TaskQueue* work_queue);
 
   // Disconnects |this| from the parent message loop.
   void WillDestroyCurrentMessageLoop();
 
+  // This should be called when it's ready for scheduling work.
+  void StartScheduling();
+
+  // Returns true if this has no queued tasks.
+  bool empty();

[danakj, 2015/04/24 20:54:39]

IsEmpty

[Nico, 2015/04/24 21:31:15]

style nit: lower_names() only for trivial methods. this one takes a lock, so
it's not trivial

[kinuko, 2015/04/27 16:36:04]

Done. (Removed this method)

+
  private:
   friend class RefCountedThreadSafe<IncomingTaskQueue>;
   virtual ~IncomingTaskQueue();
 
   // Calculates the time at which a PendingTask should run.
   TimeTicks CalculateDelayedRuntime(TimeDelta delay);
 
   // Adds a task to |incoming_queue_|. The caller retains ownership of
   // |pending_task|, but this function will reset the value of
   // |pending_task->task|. This is needed to ensure that the posting call stack
@@ skipping 19 matching lines @@
   int next_sequence_num_;
 
   // True if our message loop has already been scheduled and does not need to be
   // scheduled again until an empty reload occurs.
   bool message_loop_scheduled_;
 
   // True if we always need to call ScheduleWork when receiving a new task, even
   // if the incoming queue was not empty.
   const bool always_schedule_work_;
 
+  // False until StartScheduling() is called.
+  bool is_ready_for_scheduling_ = false;

[danakj, 2015/04/24 20:54:39]

please initialize it in the constructor where others are init

[Nico, 2015/04/24 21:31:15]

nit: let's not mix member initialization style in one class

[kinuko, 2015/04/27 16:36:04]

Done.

+
   DISALLOW_COPY_AND_ASSIGN(IncomingTaskQueue);
 };
 
 }  // namespace internal
 }  // namespace base
 
 #endif  // BASE_MESSAGE_LOOP_INCOMING_TASK_QUEUE_H_