cc: Fix source_offset computation for fixed-position layers
The source offset of a fixed-position layer is the offset from its
layer tree parent to that layer's transform tree parent. This CL
makes PropertyTreeBuilder correctly compute this value when a
layer's fixed-position container happens to be the same as its
layer tree parent. PropertyTreeBuilder previously assumed that in
this case, the offset from the layer tree parent to its transform
tree parent is 0, but this isn't necessarily the case, since the
layer tree parent won't necessarily have its own transform node.
This makes virtual/rootlayerscrolls/fast/scrolling/fixed-position-scroll-into-view.html
pass with verification enabled.
BUG=497806
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
Review URL: https://codereview.chromium.org/1220953004
Cr-Commit-Position: refs/heads/master@{#337252}
2 files changed
