This document gives an overview of the paint component of cc.
cc/paint is a replacement for SkPicture/SkCanvas/SkPaint recording data structures throughout the Chrome codebase, primarily meaning Blink and ui. The reason for a separate data structure is to change the way that recordings are stored to improve transport and recording performance.
Skia will still be the ultimate backend for raster, and so any place in code that still wants to raster directly (either for test expectations or to create an SkImage, for example) should continue to use Skia data structures.
As this component is used in both Blink and ui, it should only include files that Blink is also allowed to depend on. This means not including base/ or using std data structures publicly.
This is why cc/paint uses sk_sp reference counting at the moment as a compromise between Blink and chrome style.