Clarification on UMA metrics for Windows 7,8 font scanning

Clarify that the ReadyTime metric includes a scheduling delay,
while the BuildTime metrics does not.

Bug: 627143
Change-Id: Id69e63b63f281221054e834851ea81e93c19a209
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1754028
Auto-Submit: Dominik Röttsches <drott@chromium.org>
Commit-Queue: Dominik Röttsches <drott@chromium.org>
Commit-Queue: Stephen Chenney <schenney@chromium.org>
Reviewed-by: Stephen Chenney <schenney@chromium.org>
Cr-Commit-Position: refs/heads/master@{#686921}
1 file changed