Jochen points out that there are other places too (eg https://codereview.chromium.org/988893003/diff/480001/src/DEPS), so fmeawad is probably a pretty good owner.

(see eg comments 4 and 5 on  bug 427900  for motivation)

Deleted #2 as it had a wrong related bug number,

It should say:
(see eg comments 4 and 5 on  bug 472900  for motivation)

The main concern as stated in the other bug ( bug 472900 ):
"The point is we _never_ want to have to make changes to base and have to hunt other repos and update them. i.e. this is independent of how often base changes."

I would argue that this is not the case here, the common directory was specially designed such that it has no dependency on base (despite living in base), as we import a single header file (https://cs.chromium.org/chromium/src/base/trace_event/common/trace_event_common.h) in other repos to make sure that we can propagate new TRACE_EVENT_* macros quickly.
The functionality that depends on base lives in trace-event.h instead.

It lives in base as the rest of the tracing code does live there.

Possible solutions:
1- Copy that file in V8 (which we do not want to do as this will make the V8 copy fall out of sync quickly), as this file tends to be very active at times.
2- Move it out of base, but that does not solve the problem entirely as mentioned in the original thread that other directories in chrome might be as active.
3- Move it to a third party, and have chrome and V8 depend on it, maybe move it to catapult or something.

Jochen, WDYT?

2) and 3) sound both fine

Oystein, can we move common out of base?

trace_event/common/ is specifically designed to not include any outside headers, and be exported as a separate Git repo. If v8 imports and uses the latter as a DEPS (which I believe it does for the main tracing implementation?), then there's no difference between that and jochen's point 3 from the viewpoint of v8. Essentially, where the Git repo is exported from is an implementation detail.

The reason from chrome's viewpoint of doing it like this, is so the rest of base/ can also easily use tracing.