GitLab

BrowserControllerImpl::DidFinishNavigation can be called while
destroying WebContents:

https://cs.chromium.org/chromium/src/content/browser/web_contents/web_contents_impl.cc?rcl=81163fe37074bf1ea2bb5a76fe88b2f49e86f23a&l=694
https://cs.chromium.org/chromium/src/content/browser/frame_host/navigation_request.cc?rcl=81163fe37074bf1ea2bb5a76fe88b2f49e86f23a&l=1062

This led to a nullptr dereference.

Bug: 1021041
Change-Id: I1894912ed77e377dd0e1ffa2b746921f13f392b2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1897833
Auto-Submit: Pavel Shmakov <pshmakov@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#712649}