At the moment request tracing for REST calls is enabled by setting the
'trace' or 'trace=<trace-id>' request parameter. This is good for manual
use since adding the request parameter to the URL is very easy and can
be done quickly.
For providing copy-pastable examples for how to do tracing this is not
ideal, since it depends on the concrete URL how the request parameter
would need to be set, e.g. it can be that '?trace' or '&trace' needs to
be appended depending on whether the URL already contains request
parameters or not.
With this change we now support enabling request tracing for REST calls
also by setting a 'X-Gerrit-Trace' header in the request. For manual use
this is less easy but it makes providing copy-pastable examples for how
to do tracing easier as one can now do:
curl -D /tmp/gerrit -H X-Gerrit-Trace URL
grep X-Gerrit-Trace /tmp/gerrit
Change-Id: I793ca9fff83ef23f5720390931599a9a85e868c7
Signed-off-by: Edwin Kempin <ekempin@google.com>