GitLab

If a prerender finishes after a navigation, the page_ is no longer the
correct one. Adds an early return case from the previous DCHECKs.

Bug: 1116966
Change-Id: Iee1ca67d1a257a2390ff372dff94634db079197c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2359552
Auto-Submit: Robert Ogden <robertogden@chromium.org>
Commit-Queue: Ryan Sturm <ryansturm@chromium.org>
Reviewed-by: Ryan Sturm <ryansturm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#798720}