[telemetry] Add ability to add metadata to the trace data

[telemetry] Add ability to add metadata to the trace data

After this is in, we can add the Telemetry clock domain as trace
metadata, which will allow us to

  1) Sync clocks between Chrome and Telemetry
  2) Stop getting the error about 'a clock domain cannot sync with
     itself' that forced a revert of https://crrev.com/1980773002/

BUG=catapult:#2341

Committed: https://chromium.googlesource.com/external/github.com/catapult-project/catapult/+/f29f40079136c1a5f3a112b03367cb5ead1f18be

[charliea (OOO until 10-5), 2016-05-23 13:13:47]

charliea@chromium.org changed reviewers:
+ nednguyen@google.com

[nednguyen, 2016-05-23 15:22:07]

On 2016/05/23 13:13:47, charliea wrote:

Why is this metadata at the container level? According to the last discussion
about trace container format, I think this metadata should be embedded in
telemetry trace.

[charliea (OOO until 10-5), 2016-05-23 18:15:29]

Description was changed from

==========
[telemetry] Add ability to add metadata to the trace data

After this is in, we can add the Telemetry clock domain as trace
metadata, which will allow us to

  1) Sync clocks between Chrome and Telemetry
  2) Stop getting the error about 'a clock domain cannot sync with
     itself' that forced a revert of https://crrev.com/1980773002/

BUG=catapult:#2341
==========

to

==========
[telemetry] Add ability to add metadata to the trace data

After this is in, we can add the Telemetry clock domain as trace
metadata, which will allow us to

  1) Sync clocks between Chrome and Telemetry
  2) Stop getting the error about 'a clock domain cannot sync with
     itself' that forced a revert of https://crrev.com/1980773002/

BUG=catapult:#2341
==========

[charliea (OOO until 10-5), 2016-05-23 19:36:05]

Patchset #2 (id:20001) has been deleted

[charliea (OOO until 10-5), 2016-05-23 19:36:41]

Rewrote this CL to match what we discussed offline. PTAL

[nednguyen, 2016-05-23 19:42:00]

https://codereview.chromium.org/2007533002/diff/60001/telemetry/telemetry/tim...
File telemetry/telemetry/timeline/trace_data.py (right):

https://codereview.chromium.org/2007533002/diff/60001/telemetry/telemetry/tim...
telemetry/telemetry/timeline/trace_data.py:212: 
This should also assert that self._raw_data[part.raw_field_name] is None/empty
to avoid case people mistakenly overwrite trace

[charliea (OOO until 10-5), 2016-05-23 19:47:33]

PTAL

https://codereview.chromium.org/2007533002/diff/60001/telemetry/telemetry/tim...
File telemetry/telemetry/timeline/trace_data.py (right):

https://codereview.chromium.org/2007533002/diff/60001/telemetry/telemetry/tim...
telemetry/telemetry/timeline/trace_data.py:212: 
On 2016/05/23 19:42:00, nednguyen wrote:
> This should also assert that self._raw_data[part.raw_field_name] is None/empty
> to avoid case people mistakenly overwrite trace

Done.

[nednguyen, 2016-05-23 19:48:59]

lgtm

[charliea (OOO until 10-5), 2016-05-23 19:49:07]

The CQ bit was checked by charliea@chromium.org

[commit-bot: I haz the power, 2016-05-23 19:49:12]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/2007533002/80001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/2007533002/80001

[commit-bot: I haz the power, 2016-05-23 20:10:44]

Description was changed from

==========
[telemetry] Add ability to add metadata to the trace data

After this is in, we can add the Telemetry clock domain as trace
metadata, which will allow us to

  1) Sync clocks between Chrome and Telemetry
  2) Stop getting the error about 'a clock domain cannot sync with
     itself' that forced a revert of https://crrev.com/1980773002/

BUG=catapult:#2341
==========

to

==========
[telemetry] Add ability to add metadata to the trace data

After this is in, we can add the Telemetry clock domain as trace
metadata, which will allow us to

  1) Sync clocks between Chrome and Telemetry
  2) Stop getting the error about 'a clock domain cannot sync with
     itself' that forced a revert of https://crrev.com/1980773002/

BUG=catapult:#2341

Committed:
https://chromium.googlesource.com/external/github.com/catapult-project/catapu...
==========

[commit-bot: I haz the power, 2016-05-23 20:10:45]

Committed patchset #4 (id:80001) as
https://chromium.googlesource.com/external/github.com/catapult-project/catapu...