Besides the general utility of being able to rely on having these categories in the trace, the particular motivation is this: https://github.com/catapult-project/catapult/issues/1818

Any movement on this?

It looks like TracingConfig is logged as a metadata event.

TraceConfig	
{enable_argument_filter: false,
 enable_sampling: false,
 enable_systrace: true,
 excluded_categories: ["AccountFetcherService",
...
                       "worker.scheduler"],
 included_categories: ["disabled-by-default-blink.debug.layout.trees"],
 record_mode: "record-until-full"}

However, this doesn't include the default categories that are enabled, so if the list of default categories changes (which can happen when somebody adds a macro somewhere that we don't know about), then this is fragile.

But it sounds like this is unmotivated? So close this?

Ah, if it's already there, then probably no need to do anything about this bug.

Actually Ben, how do you know those event are logged?

I don't see them after clicking "M" button in the trace https://console.developers.google.com/m/cloudstorage/b/chrome-telemetry-output/o/trace-file-id_3-2016-10-03_13-31-12-31410.html

The "M" button only shows the "metaData" JSON dict, it doesn't scan for any __metadata events in the stream AFAIK.

That link is 403 for me, but I see the TraceConfig metadata event in chrome 53.0.2785. Can you see the product-version in that trace's metadata?

https://codesearch.chromium.org/chromium/src/content/browser/tracing/tracing_controller_impl.cc?sq=package:chromium&dr=CSs&rcl=1475508985&l=325

https://chromium.googlesource.com/chromium/src/+blame/master/base/trace_event/trace_config.cc
https://chromium.googlesource.com/chromium/src/+blame/master/content/browser/tracing/tracing_controller_impl.cc

Hmhh, I think we do have the code for scan __metadata events:

https://github.com/catapult-project/catapult/blob/master/tracing/tracing/extras/importer/trace_event_importer.html#L613

Ben, Chrome version of the trace is 55.0.2880.0

The importer recognizes metadata events by their phase ('M'), not their category ("__metadata" or whatever).

I managed to get that file. It does not contain events in the __metadata category.

Does the benchmark need to add "__metadata" to the list of enabled categories?

It looks like the metadata event that contains "product-version" is not generated using the normal macros. It looks like it is directly appended to the file without checking whether any category is enabled.

Maybe TraceConfig should be added to the TracingController metadata dict instead of using TRACE_EVENT_API_ADD_METADATA_EVENT?

This issue has been Available for over a year. If it's no longer important or seems unlikely to be fixed, please consider closing it out. If it is important, please re-triage the issue.

Sorry for the inconvenience if the bug really should have been left as Available. If you change it back, also remove the "Hotlist-Recharge-Cold" label.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Fixed a long time ago in https://chromium-review.googlesource.com/737049