In order to make the Flutter engine's rendering system support multiple views, we need to change multiple components across the engine. The plan can be found in design doc flutter.dev/go/multi-view-pipeline-and-rasterizer. Items are listed below. The order of the items does not represent dependency, and some items can be developed in parallel.

• Item 1: Eliminate violations of the rendering rule (Enforce the rule of calling FlutterView.Render engine#45300)
• Item 2: Make the pipeline support multiple views. The Animator should collect (instead of dispatching) the layer tree in Render and dispatch them at the end of BeginFrame (Multiview pipeline engine#44473).
• Item 3: Make the Rasterizer's structure compatible with multiple views. (Multi-view Rasterizer  engine#45512)
• Item 4: Allow the ExternalViewEmbedder to handle multiple views. (Multiview backing store engine#51722, Make EmbedderExternalViewEmbedder present to the correct view engine#51719, Multiview ExternalViewEmbedder engine#46169)
• Abandoned: Allow the RasterCache to handle multiple views.
  • Per @/stuartmorgan (I can't find the source for now) the raster cache only improves performance on mobile in specific cases, and should not help desktop. The raster cache should be made optional.