[colabutils] Cold start time profiling

This change adds a utility for measuring the cold startup time of Chrome
on Android.

Bug: 443799489
Change-Id: Ic090be6639f81cd2d2f25582d5327e4c33f95b09
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6962414
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Commit-Queue: Anand Ravi <anandrv@google.com>
Cr-Commit-Position: refs/heads/main@{#1516881}
NOKEYCHECK=True
GitOrigin-RevId: 66cc05f943b8934dc0f3874ddc1c8b1649ec327b