GitLab

Record the number of files (and their unsent samples) from previous
runs and make those values into stability metrics.

The metrics precisely simulate the INTERNAL_PROFILE behavior and are
only enabled for WebView.

The patch also extends the metrics for used size to M87.

Bug: 1076549

Change-Id: I0356899f13b8b89b9823c81d1eb748ef8ca3ee5d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2293321Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Reviewed-by: Brian White <bcwhite@chromium.org>
Commit-Queue: Tao Bai <michaelbai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#801165}