Make base::PendingTask support ConvertableToTraceFormat

base/trace_event/trace_event.h

Index: base/trace_event/trace_event.h
diff --git a/base/trace_event/trace_event.h b/base/trace_event/trace_event.h
index 4de64837161fded5fd176d1dc5136006d8521a9e..1105429fd8e261495a55a3b86c3fc8b036e8b331 100644
--- a/base/trace_event/trace_event.h
+++ b/base/trace_event/trace_event.h
@@ -438,11 +438,9 @@ TRACE_EVENT_API_CLASS_EXPORT extern \
 
 // Implementation detail: internal macro to trace a task execution with the
 // location where it was posted from.
-#define INTERNAL_TRACE_TASK_EXECUTION(run_function, task)                 \
-  TRACE_EVENT2("toplevel", run_function, "src_file",                      \
-               (task).posted_from.file_name(), "src_func",                \
-               (task).posted_from.function_name());                       \
-  TRACE_HEAP_PROFILER_API_SCOPED_TASK_EXECUTION INTERNAL_TRACE_EVENT_UID( \
+#define INTERNAL_TRACE_TASK_EXECUTION(run_function, task)                      \

[Sami, 2016/10/04 11:25:31]

I believe there are a number of tools (e.g., Lighthouse, maybe also Telemetry)
that parse this information. Could we try to track them down and coordinate this
change with them?

+  TRACE_EVENT1("toplevel", run_function, "src_info", (task).GetTracingInfo()); \
+  TRACE_HEAP_PROFILER_API_SCOPED_TASK_EXECUTION INTERNAL_TRACE_EVENT_UID(      \
       task_event)((task).posted_from.file_name());
 
 namespace trace_event_internal {