[CompositeAfterPaint] Fix frame overlay invalidation

In CAP, some frame overlays paint contents directly into display items
without a composited layer. Now invalidate the FrameOverlay as
DisplayItemClient in UpdatePrePaint() (just like pre-CAP always
invalidates the GraphicsLayer).

Bug: 1047359
Change-Id: Ic3aa9c35f390bea4b0cd142c5a3a01b090cf4909
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2261134
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Reviewed-by: Philip Rogers <pdr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#781882}