chore: cherry-pick 8c346e3cd9 from chromium.

[ppontes]

ui: CHECK that UnPremultiply is passed a 32bpp image

To do otherwise results in accessing random data.

BUG=1147430
TEST=none

(cherry picked from commit 1f673896837ab8c687d93fec604c96c78c7f679b)

Change-Id: Icedacbaac64cad3fc903e6423c6f9aad8c1e8cb5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2531118
Commit-Queue: danakj danakj@chromium.org
Reviewed-by: danakj danakj@chromium.org
Cr-Original-Commit-Position: refs/heads/master@{#826300}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2538047
Reviewed-by: Scott Violet sky@chromium.org
Commit-Queue: Scott Violet sky@chromium.org
Cr-Commit-Position: refs/branch-heads/4240@{#1452}
Cr-Branched-From: f297677702651916bbf65e59c0d4bbd4ce57d1ee-refs/heads/master@{#800218}

Release Notes

Notes: backported the fix to CVE-2020-16024: Heap buffer overflow in UI.

[release-clerk]

Release Notes Persisted

backported the fix to CVE-2020-16024: Heap buffer overflow in UI.