Currently startTime is 0, which is a problem because getEntries()
methods all sort by startTime. To help with this problem, we set the
startTime to renderTime, if available, or to loadTime, if renderTime is
nt available.

Bug: 965505
Change-Id: Ie70b69269f7ce4be0fdc94f33a44a84e062d3ba5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1719379
Reviewed-by: Yoav Weiss <[email protected]>
Commit-Queue: Nicolás Peña Moreno <[email protected]>
Cr-Commit-Position: refs/heads/master@{#681147}