Add trace code to track all posted tasks in message_loop.

base/threading/worker_pool_posix.h

 // 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.
 //
 // The thread pool used in the POSIX implementation of WorkerPool dynamically
 // adds threads as necessary to handle all tasks.  It keeps old threads around
 // for a period of time to allow them to be reused.  After this waiting period,
 // the threads exit.  This thread pool uses non-joinable threads, therefore
 // worker threads are not joined during process shutdown.  This means that
 // potentially long running tasks (such as DNS lookup) do not block process
@@ skipping 37 matching lines @@
 
   struct PendingTask {
     PendingTask(const tracked_objects::Location& posted_from,
                 const base::Closure& task);
     ~PendingTask();
     // TODO(ajwong): After we figure out why Mac's ~AtExitManager dies when
     // destructing the lock, add in extra info so we can call
     // tracked_objects::TallyADeathIfActive() and
     // tracked_objects::TallyABirthIfActive correctly.
 
+    const tracked_objects::Location posted_from;
+
     // The task to run.
     base::Closure task;
   };
 
   // All worker threads will share the same |name_prefix|.  They will exit after
   // |idle_seconds_before_exit|.
   PosixDynamicThreadPool(const std::string& name_prefix,
                          int idle_seconds_before_exit);
   ~PosixDynamicThreadPool();
 
@@ skipping 38 matching lines @@
   // Only used for tests to ensure correct thread ordering.  It will always be
   // NULL in non-test code.
   scoped_ptr<ConditionVariable> num_idle_threads_cv_;
 
   DISALLOW_COPY_AND_ASSIGN(PosixDynamicThreadPool);
 };
 
 }  // namespace base
 
 #endif  // BASE_THREADING_WORKER_POOL_POSIX_H_