[local_storage] Add compression_format metric

Add a new metric to track compression formats. Currently only used by
blobfs, but can be used by other filesystems too.
Generate a per-device histogram report.

CL which logs these metrics:
https://fuchsia-review.googlesource.com/c/fuchsia/+/375658

Change-Id: I87e0decf0a02462d86d3ae37ce31184f0a990459
Reviewed-on: https://fuchsia-review.googlesource.com/c/cobalt-registry/+/375451
Commit-Queue: Rasha Eqbal <rashaeqbal@google.com>
Reviewed-by: Mitch Rudominer <rudominer@google.com>
Reviewed-by: Gianfranco Valentino <gevalentino@google.com>
1 file changed
tree: 2fa91992d1b0f08240d1cef9c31c9bca5e20f465
  1. cobalt_internal/
  2. fuchsia/
  3. .gitignore
  4. BUILD.gn
  5. check.py
  6. OWNERS
  7. projects.yaml