grouping and content.

• PaintChunk: groups sequential display items that share the same property‑tree state and cull/visibility; it’s the unit we layerize and invalidate.

• DisplayItemList: the recorded Skia/paint operations (text, images, paths, etc.). This split lets us reason about “where/how to draw” (chunk) vs. “what to draw” (items). (Chromium Git Repositories)

Hands off to: PaintArtifactCompositor for compositing decisions, then PropertyTreeManager to mirror trees into cc.