metrics: read /sys/class/block/*/stat correctly

TEST=unit tests, manual tested on panther_embedded
BUG=chromium:415118

Change-Id: I849a9b7849a27d29d9d24bb1575f113e43716bd5
Reviewed-on: https://chromium-review.googlesource.com/218504
Reviewed-by: Bertrand Simonnet <bsimonnet@chromium.org>
Commit-Queue: Nathan Bullock <nathanbullock@google.com>
Tested-by: Nathan Bullock <nathanbullock@google.com>
2 files changed
tree: 8ad52f3a7e195014db519c38d5087a03dcc50370
  1. metrics/