Revert of Make flow event traces disabled-by-default, and rename "ipc" and "task"

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 dd4580c645a788e9707d1d0ff9aa9fe118c23adc..bbf7cd3990c4cb0f391bf2a0c39b0b4e8d170407 100644
--- a/base/message_loop/message_loop.cc
+++ b/base/message_loop/message_loop.cc
@@ -416,14 +416,14 @@
   tracked_objects::TrackedTime start_time =
       tracked_objects::ThreadData::NowForStartOfRun(pending_task.birth_tally);
 
-  TRACE_EVENT_FLOW_END1(TRACE_DISABLED_BY_DEFAULT("toplevel.flow"),
-      "MessageLoop::PostTask", TRACE_ID_MANGLE(GetTaskTraceID(pending_task)),
+  TRACE_EVENT_FLOW_END1("task", "MessageLoop::PostTask",
+      TRACE_ID_MANGLE(GetTaskTraceID(pending_task)),
       "queue_duration",
       (start_time - pending_task.EffectiveTimePosted()).InMilliseconds());
   // When tracing memory for posted tasks it's more valuable to attribute the
   // memory allocations to the source function than generically to "RunTask".
   TRACE_EVENT_WITH_MEMORY_TAG2(
-      "toplevel", "MessageLoop::RunTask",
+      "task", "MessageLoop::RunTask",
       pending_task.posted_from.function_name(),  // Name for memory tracking.
       "src_file", pending_task.posted_from.file_name(),
       "src_func", pending_task.posted_from.function_name());