Add queued_time_ms trace for events in message loop

base/message_loop/message_loop.cc

 // 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.
 
 #include "base/message_loop/message_loop.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
@@ skipping 441 matching lines @@
   deferred_non_nestable_work_queue_.pop();
 
   RunTask(pending_task);
   return true;
 }
 
 void MessageLoop::RunTask(const PendingTask& pending_task) {
   TRACE_EVENT_FLOW_END0("task", "MessageLoop::PostTask",
       TRACE_ID_MANGLE(GetTaskTraceID(pending_task, this)));
   TRACE_EVENT2("task", "MessageLoop::RunTask",
-               "src_file", pending_task.posted_from.file_name(),
-               "src_func", pending_task.posted_from.function_name());
+               "src", pending_task.posted_from.ToTraceFormat(),
+               "queued_time_ms",
+               pending_task.DurationSinceExpectedRunTime().InMilliseconds());

[jar (doing other things), 2013/07/08 17:08:33]

Possibly not a big deal...  I'm always wary of the cost of conversion to
milliseconds.  It uses 64 bit arithmetic (on Windows) to do a divide-by-1000,
which commonly requires calling a library call (sadly), and hence is also pretty
expensive.

[Xianzhu, 2013/07/08 18:51:39]

Changed DurationSinceExpectedRunTime() to return tracked_objects::Duration.

+
   DCHECK(nestable_tasks_allowed_);
   // Execute the task and assume the worst: It is probably not reentrant.
   nestable_tasks_allowed_ = false;
 
   // Before running the task, store the program counter where it was posted
   // and deliberately alias it to ensure it is on the stack if the task
   // crashes. Be careful not to assume that the variable itself will have the
   // expected value when displayed by the optimizer in an optimized build.
   // Look at a memory dump of the stack.
   const void* program_counter =
@@ skipping 351 matching lines @@
       fd,
       persistent,
       mode,
       controller,
       delegate);
 }
 
 #endif
 
 }  // namespace base