Add trace code to track all posted tasks in message_loop.

base/message_loop.cc

Index: base/message_loop.cc
diff --git a/base/message_loop.cc b/base/message_loop.cc
index 19ce904120de6549656a923a422915dd77ae3c73..d5a08da113d50eb22b23ecf1f5385827b8e3cb1d 100644
--- a/base/message_loop.cc
+++ b/base/message_loop.cc
@@ -9,6 +9,7 @@
 #include "base/bind.h"
 #include "base/compiler_specific.h"
 #include "base/debug/alias.h"
+#include "base/debug/trace_event.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
@@ -458,6 +459,9 @@ bool MessageLoop::ProcessNextDelayedNonNestableTask() {
 }
 
 void MessageLoop::RunTask(const PendingTask& pending_task) {
+  TRACE_EVENT2("base", "MessageLoop::RunTask",

[darin (slow to review), 2011/08/31 21:40:55]

does this cause the FROM_HERE strings to start getting linked into chrome.dll? 
do you know how that impacts the codesize of chrome.dll?

+      "source", pending_task.birth_location.file_line(),
+      "function", pending_task.birth_location.function_name().data());
   DCHECK(nestable_tasks_allowed_);
   // Execute the task and assume the worst: It is probably not reentrant.
   nestable_tasks_allowed_ = false;
@@ -467,7 +471,8 @@ void MessageLoop::RunTask(const PendingTask& pending_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 = pending_task.birth_program_counter;
+  const void* program_counter =
+    pending_task.birth_location.program_counter();

[darin (slow to review), 2011/08/31 21:40:55]

nit: 4 space indent for line continuation

[jbates, 2011/09/01 23:01:52]

Done.

   base::debug::Alias(&program_counter);
 
   HistogramEvent(kTaskRunEvent);
@@ -765,9 +770,9 @@ MessageLoop::PendingTask::PendingTask(
     : task(task),
       time_posted(TimeTicks::Now()),
       delayed_run_time(delayed_run_time),
+      birth_location(posted_from),
       sequence_num(0),
-      nestable(nestable),
-      birth_program_counter(posted_from.program_counter()) {
+      nestable(nestable) {
 #if defined(TRACK_ALL_TASK_OBJECTS)
   post_births = tracked_objects::ThreadData::TallyABirthIfActive(posted_from);
 #endif  // defined(TRACK_ALL_TASK_OBJECTS)