Correct background image offset for paginated document canvas.
A paginated document canvas background (typically defined on BODY or
HTML) should resume on a next page where it left off at the previous
page, so include the stitched page area offset for the current page. Not
doing this would not only give incorrect offsets into the background
image for all pages but the first, but would also repeat the image once
on every page, even if it shouldn't repeat (tile).
Bug: 351332645
Change-Id: Ifd28a1bd31ee52baa7957d1283b14df08edb1082
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5682985
Reviewed-by: Xianzhu Wang wangxianzhu@chromium.org
Auto-Submit: Morten Stenshorne mstensho@chromium.org
Commit-Queue: Xianzhu Wang wangxianzhu@chromium.org
Cr-Commit-Position: refs/heads/main@{#1324291}