tracing: ensure __metadata events are always added to the trace

tracing: ensure __metadata events are always added to the trace

This is a temporary workaround to deal with the fact that some
metadata events, such as TRACE_EVENT_CLOCK_SYNC_*, are not added to
the trace if the category filter disables the default categories (-*).
A proper long-term fix is being discussd in the attached bug.

BUG=618054
Committed: https://crrev.com/d5fbde04754b74a75c0d75878f275e37791118b1
Cr-Commit-Position: refs/heads/master@{#398398}

[Primiano Tucci (use gerrit), 2016-06-07 20:42:59]

The CQ bit was checked by primiano@chromium.org to run a CQ dry run

[Primiano Tucci (use gerrit), 2016-06-07 20:43:12]

primiano@chromium.org changed reviewers:
+ charliea@chromium.org, oysteine@chromium.org

[oystein (OOO til 10th of July), 2016-06-07 20:46:08]

lgtm

[Primiano Tucci (use gerrit), 2016-06-07 20:53:28]

The CQ bit was unchecked by primiano@chromium.org

[Primiano Tucci (use gerrit), 2016-06-07 20:53:32]

The CQ bit was checked by primiano@chromium.org

[commit-bot: I haz the power, 2016-06-07 21:03:20]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/2047793002/1

[commit-bot: I haz the power, 2016-06-07 22:16:55]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-06-07 22:18:05]

Description was changed from

==========
tracing: ensure __metadata events are always added to the trace

This is a temporary workaround to deal with the fact that some
metadata events, such as TRACE_EVENT_CLOCK_SYNC_*, are not added to
the trace if the category filter disables the default categories (-*).
A proper long-term fix is being discussd in the attached bug.

BUG=618054
==========

to

==========
tracing: ensure __metadata events are always added to the trace

This is a temporary workaround to deal with the fact that some
metadata events, such as TRACE_EVENT_CLOCK_SYNC_*, are not added to
the trace if the category filter disables the default categories (-*).
A proper long-term fix is being discussd in the attached bug.

BUG=618054

Committed: https://crrev.com/d5fbde04754b74a75c0d75878f275e37791118b1
Cr-Commit-Position: refs/heads/master@{#398398}
==========

[commit-bot: I haz the power, 2016-06-07 22:18:06]

Patchset 1 (id:??) landed as
https://crrev.com/d5fbde04754b74a75c0d75878f275e37791118b1
Cr-Commit-Position: refs/heads/master@{#398398}