GitLab

In order to prevent crashes due to unchecked uses of GetWindowAndroid(),
this CL creates dialog instance only if window is successfully
retrieved. Plus, null-checks for dialog instance are needed before
using it.

Bug: 1051035, 1049090
Change-Id: Icae3747474398b09c73372a0879f3df7a2afa978
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2294761
Commit-Queue: Vasilii Sukhanov <vasilii@chromium.org>
Reviewed-by: Vasilii Sukhanov <vasilii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#789443}