GitLab

exo::Surface might be unavailable when:
- Just after the Activity starts
- It's getting recreated when resizing the window.

BUG=925769
TEST=manually

Change-Id: Ie6dbf9349aeec6f65366fb3d1f077135c0439dd8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1493689Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Commit-Queue: Ryo Hashimoto <hashimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#649741}