Trace memory records source function for posted tasks instead of "RunTask"

base/message_loop/message_loop.cc

Index: base/message_loop/message_loop.cc
diff --git a/base/message_loop/message_loop.cc b/base/message_loop/message_loop.cc
index 92039e237b885fbdadde39d3269554127a73df9d..e1f0258a9c757a112e2c0818aaf2a33dea2adf3d 100644
--- a/base/message_loop/message_loop.cc
+++ b/base/message_loop/message_loop.cc
@@ -458,9 +458,14 @@ void MessageLoop::RunTask(const PendingTask& pending_task) {
       TRACE_ID_MANGLE(GetTaskTraceID(pending_task)),
       "queue_duration",
       (start_time - pending_task.EffectiveTimePosted()).InMilliseconds());
-  TRACE_EVENT2("task", "MessageLoop::RunTask",
-               "src_file", pending_task.posted_from.file_name(),
-               "src_func", pending_task.posted_from.function_name());
+  // When tracing memory for posted tasks it's more valuable to attribute the
+  // memory allocations to the source function than generically to "RunTask".
+  // Use a TRACE_EVENT2 variation to record a normal trace event but attribute
+  // the memory to the pending task's source function name.
+  TRACE_EVENT2_MEMORY_ARG2(
+      "task", "MessageLoop::RunTask",
+      "src_file", pending_task.posted_from.file_name(),
+      "src_func", pending_task.posted_from.function_name());
 
   DCHECK(nestable_tasks_allowed_);
   // Execute the task and assume the worst: It is probably not reentrant.