Today, we allow developers to enable debug checker-boarding of offscreen rendered layers as well raster cached images. Impeller will not support the raster cache but it needs to replicate offscreen rendered layer contents (the so called "save layered" contents).

Today, this checker-boarding is implemented in flow via Skia APIs directly (which is also why it doesn't work with Impeller since it bypasses the display list). But with all the work to collapse and elide render passes, it makes sense to have a context or render pass option that makes Impeller checkerboard contents that were actually rendered via a separate render pass.