[PWA/Nav Capture] Record latency for navigations handled in browser

This CL adds logic for measuring the latency of the navigation capturing
process and reparenting inside the browser process. It does so by
plumbing the time when the navigation capturing process is asked to
create a frame via the LaunchParams all the way to when the params are
enqueued, so that a rough estimation of the latency of the navigation
capturing process is obtained, as launch params are only enqueued after
navigation commits. This isn't a very accurate representation of the
whole navigation latency starting from a link click, which is
complicated, and involves sending a lot of information from the renderer
to the browser and back.

Tested manually and automatically using the existing browser tests which
verify navigation capturing where params.browser is populated, including
the redirection ones.

Bug: 409792072
Change-Id: Id4bf56b85f8285e8880a35aad0e48b146ff05fd1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6499169
Reviewed-by: Daniel Murphy <dmurph@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: May Siem <msiem@chromium.org>
Commit-Queue: Dibyajyoti Pal <dibyapal@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1455044}