[WebLayer] Add another test for WebView/WebLayer in same process

We had a test loading WebLayer first, this adds another test loading
WebView first. This extra coverage will be nice to make sure a couple
perf ideas I have in mind don't break anything.

Bug: 1146438
Change-Id: I32225a6d79645ed1f0cd881bfb71261c1d5e9804
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2651448


Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Clark DuVall <cduvall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#847431}