cc::ScrollTree

The source text provides an exhaustive technical overview of the Scroll Property Tree (cc::ScrollTree) within the Chromium compositor architecture, which is critical for enabling smooth, off-main-thread scrolling. It explains that the ScrollTree captures the hierarchy and properties of scrollable elements, utilizing individual ScrollNodes to store geometric data (like content and container bounds) and behavioral flags (such as whether scrolling is handled on the main thread or if scroll snapping is active). Furthermore, the text details how the ScrollTree works in close coordination with the Transform Tree to apply scroll-induced translations and how it manages the entire scrolling lifecycle, from input event hit-testing and scroll latching to handling overscroll and synchronizing scroll offsets back to the main thread (Blink) via commit mechanisms. This system ensures that complex features like pinch-zoom, sticky positioning, and scroll-linked animations operate correctly and efficiently on the compositor thread.