The Flat Architecture of Chromium Paint Operations

Chromium’s paint data system is designed as a flat, sequential stream of operations rather than a complex tree of nodes. While a shallow C++ inheritance hierarchy exists for the code classes, the actual recorded data is stored in contiguous buffers resembling a display-list tape. True nesting occurs only through specific container-like objects, such as DrawRecordOp and DrawScrollingContentsOp, which reference nested records or entire display lists. These special operations delegate tasks like rasterization and memory accounting to their internal components, though they are often flattened during serialization for efficiency. Ultimately, the system relies on stack-based state ops like save and restore to manage hierarchy, ensuring high performance for rendering and transport.