Capture interactive duration when interactive not hit.

This is a follow-up to crrev/1512494 to fix the case where a page never
hits interactive.  In this case, the entire duration of the page should
be pre-interactive (it was reporting as post due to the error). This
fixes that error and adds a unit test for that case.

Bug: 937298
Change-Id: I1590729dac404378d037ef03d1d2022bd583c109
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1534194
Reviewed-by: Charlie Harrison <csharrison@chromium.org>
Commit-Queue: Eric Robinson <ericrobinson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#643096}
2 files changed