perf: Add --newonly flag that doesn't do any tracedb work.
perf: Add --newonly flag that doesn't do any tracedb work.

BUG=skia:
NOTRY=true

Change-Id: Id00a697845d516ca9e131cdac8d3997f2303aed7
Reviewed-on: https://skia-review.googlesource.com/4388
Reviewed-by: Ben Wagner <3ef7217be91069877d94f7907ce5479000772cd3@google.com>
Reviewed-by: Joe Gregorio <b9cf2471ff6d33504cafe8e6f356b732b2cadced@google.com>
Commit-Queue: Joe Gregorio <b9cf2471ff6d33504cafe8e6f356b732b2cadced@google.com>

google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot