commit 48e402acbebf2717b8e79b89dba5310d31bf95da
author wangxianzhu <wangxianzhu@chromium.org> Wed Dec 09 07:05:08 2015
committer Commit bot <commit-bot@chromium.org> Wed Dec 09 07:06:06 2015
tree bd2e496ad6823136538c15efb1af6d172b238da3
parent 4632e5f1934937d0754277023266f033dfd7b547

Fix several corner case issues of scrollbar paint invalidation

- Invalidate composited scrollbars also during paint invalidation to
  avoid unnecessary invalidation on intermediate changes;

- Invalidate also on the containing box for moved/resized composited
  non-overlay scrollbars. This ensures the expanded/shrunk areas of the
  box because of scrollbar existence/width change are invalidated. This
  is the root cause of bug 535161.

- Avoid unnecessary invalidations on overlay scrollbar changes.

BUG=535161,560418

Review URL: https://codereview.chromium.org/1491193003

Cr-Commit-Position: refs/heads/master@{#363998}