[CompositeAfterPaint] Implement dev tools overlay

For CompositeAfterPaint, create a cc::PictureLayer, and output a
ForeignlayerDisplayItem during paint.

Bug: 524134
Change-Id: I88d0678c9e5230d2197e76f89f570bf3be850064
Reviewed-on: https://chromium-review.googlesource.com/c/1391032
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#619188}
14 files changed