base: Factor task debug annotations out of MessageLoop

base/message_loop/message_loop.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_MESSAGE_LOOP_H_
 #define BASE_MESSAGE_LOOP_MESSAGE_LOOP_H_
 
 #include <queue>
 #include <string>
 
 #include "base/base_export.h"
 #include "base/basictypes.h"
 #include "base/callback_forward.h"
+#include "base/debug/task_annotator.h"
 #include "base/location.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/incoming_task_queue.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "base/message_loop/message_loop_proxy_impl.h"
 #include "base/message_loop/message_pump.h"
 #include "base/message_loop/timer_slack.h"
 #include "base/observer_list.h"
 #include "base/pending_task.h"
@@ skipping 395 matching lines @@
   bool DeferOrRunPendingTask(const PendingTask& pending_task);
 
   // Adds the pending task to delayed_work_queue_.
   void AddToDelayedWorkQueue(const PendingTask& pending_task);
 
   // Delete tasks that haven't run yet without running them.  Used in the
   // destructor to make sure all the task's destructors get called.  Returns
   // true if some work was done.
   bool DeletePendingTasks();
 
-  // Creates a process-wide unique ID to represent this task in trace events.
-  // This will be mangled with a Process ID hash to reduce the likelyhood of
-  // colliding with MessageLoop pointers on other processes.
-  uint64 GetTaskTraceID(const PendingTask& task);
+  // Returns the TaskAnnotator which is used to add debug information to posted
+  // tasks.
+  debug::TaskAnnotator* task_annotator() { return &task_annotator_; }

[eseidel, 2014/08/12 16:18:49]

Does Chromium use 'const' here?

[Sami, 2014/08/12 16:58:00]

Making the method const would require a const_cast<> around the pointer. I did a
quick search and didn't find any accessors that do that.

 
   // Loads tasks from the incoming queue to |work_queue_| if the latter is
   // empty.
   void ReloadWorkQueue();
 
   // Wakes up the message pump. Can be called on any thread. The caller is
   // responsible for synchronizing ScheduleWork() calls.
   void ScheduleWork(bool was_empty);
 
   // Start recording histogram info about events and action IF it was enabled
@@ skipping 40 matching lines @@
 #endif
 
   std::string thread_name_;
   // A profiling histogram showing the counts of various messages and events.
   HistogramBase* message_histogram_;
 
   RunLoop* run_loop_;
 
   ObserverList<TaskObserver> task_observers_;
 
+  debug::TaskAnnotator task_annotator_;
+
   scoped_refptr<internal::IncomingTaskQueue> incoming_task_queue_;
 
   // The message loop proxy associated with this message loop.
   scoped_refptr<internal::MessageLoopProxyImpl> message_loop_proxy_;
   scoped_ptr<ThreadTaskRunnerHandle> thread_task_runner_handle_;
 
   template <class T, class R> friend class base::subtle::DeleteHelperInternal;
   template <class T, class R> friend class base::subtle::ReleaseHelperInternal;
 
   void DeleteSoonInternal(const tracked_objects::Location& from_here,
@@ skipping 141 matching lines @@
 
 // Do not add any member variables to MessageLoopForIO!  This is important b/c
 // MessageLoopForIO is often allocated via MessageLoop(TYPE_IO).  Any extra
 // data that you need should be stored on the MessageLoop's pump_ instance.
 COMPILE_ASSERT(sizeof(MessageLoop) == sizeof(MessageLoopForIO),
                MessageLoopForIO_should_not_have_extra_member_variables);
 
 }  // namespace base
 
 #endif  // BASE_MESSAGE_LOOP_MESSAGE_LOOP_H_