[perf] - "Remove all" needs to remove all the traces.
[perf] - "Remove all" needs to remove all the traces.

They weren't being removed from explore-sk._dataframe.

Bug: skia:9531
Change-Id: I29d7106037b273cb5f57c2187a0fa4cf5f82cd36
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/248799
Reviewed-by: Kevin Lubick <7cdab2cfab351f23814786ba39716e90eed69047@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