[mapper] Reply to comments left in the previous CL after it was submitted.
[mapper] Reply to comments left in the previous CL after it was submitted.

This one: https://chromium-review.googlesource.com/c/1239209

R=40f3d43a28ebae3cb819288542e1c84d73d962d5@chromium.org

Change-Id: Ibd18367936f48bf339661109db884b7c3814c926
Reviewed-on: https://chromium-review.googlesource.com/1244138
Reviewed-by: Robbie Iannucci <40f3d43a28ebae3cb819288542e1c84d73d962d5@chromium.org>
Commit-Queue: Vadim Shtayura <9f116ddb1b24f6fc1916a676eb17161b6c07dfc1@chromium.org>

luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go