[CompositeAfterPaint/PE] Fix scrolling background painting of table cells

When painting the scrolling background of a table cell, we need the
same logic in BoxPainter::PaintBoxDecorationBackground() for special
display item client, paint rect and paint state.

We can't merge PaintBoxDecorationBackground() for now for BoxPainter
and TableCellPainter because table cell needs a special clip to prevent
the background from covering the border e.g. when the table cell is
painted on a seperate composited layer. We can merge them when we remove
pre-CompositeAfterPaint code path.

Bug: 524134
Change-Id: I94b891bca86ae4ddd9e689e38114e70c0e8acb51
Reviewed-on: https://chromium-review.googlesource.com/c/1401432
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#621486}
8 files changed