Chromium Internal Architecture for Composited Background Color Animation

Chromium utilizes a RenderingNG architecture that separates the main-thread pipeline from the compositor-thread to ensure smooth animations. While properties like opacity and transform are easily updated by the compositor, background-color is traditionally raster-inducing because it changes the actual pixels within a layer. To optimize this, Chromium uses a native paint-worklet infrastructure that allows the compositor to drive these animations without returning to the main thread. Blink packages a static payload of color keyframes and a progress scalar that the compositor advances to regenerate PaintRecords as needed. This process enables the system to trigger rerasterization of affected tiles while avoiding expensive main-thread style or layout passes. Consequently, the engine maintains high performance by restricting this path to simple colors that do not require complex, main-thread semantic resolution.