metrics: Make implicit MetricsLibrary d'tor explicit.

Also add 'virtual' and 'OVERRIDE' to overridden methods.

BUG=none
TEST=did a build

Change-Id: Iec71c59853b6ada38b20cea9d0605c3d39e9353f
Reviewed-on: https://chromium-review.googlesource.com/189398
Reviewed-by: Daniel Erat <derat@chromium.org>
Commit-Queue: Daniel Erat <derat@chromium.org>
Tested-by: Daniel Erat <derat@chromium.org>
2 files changed
tree: a9333d4033ada0077607169c59abbb0ed50a2ba7
  1. metrics/