Refactor RenderPosition::PositionInGraphicsLayerBacking #2

This patch moves CompositedSelectionBound.hidden assignment from
LocalFrameView to PositionInGraphicsLayerBacking() for code health.

Bug: 789870
Change-Id: I007aee8b5e6acc78c57127feb4191b94d2789852
Reviewed-on: https://chromium-review.googlesource.com/869697
Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Kent Tamura <tkent@chromium.org>
Reviewed-by: Xiaocheng Hu <xiaochengh@chromium.org>
Commit-Queue: Yoichi Osato <yoichio@chromium.org>
Cr-Commit-Position: refs/heads/master@{#530025}
3 files changed