Bounds delta change should update clip tree
This fixes LayerTreeHostCommonTest.BoundsDeltaAffectVisibleContentRect
1) When root layer is clipping, create a clip node for it.
(not confused with root clip, which is created from viewport,
and clipping root_layer's clip node is the root clip's child)
2) When root layer's bounds delta change, we need to update root
layer's clip node using root layer's new bounds.
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
Review URL: https://codereview.chromium.org/1173183002
Cr-Commit-Position: refs/heads/master@{#334647}
3 files changed
