Android: Handle gesture navigation favicon callback invoked too late

Favicon callbacks can be invoked after the navigation sheet is already
closed. There is a null check against |mModelList| but it never
becomes null. Its state should have been checked instead. This CL
checks such case correctly.

Bug: 1000220
Change-Id: I724b7c3a7d79e36a99d6c102849312e8010f2548
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1783680
Commit-Queue: Jinsuk Kim <jinsukkim@chromium.org>
Reviewed-by: Donn Denman <donnd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#692988}
1 file changed