This bugs tracks support for allowing multiple RenderingContexts. This means that a WebView might share a RenderingContext with another WebView or it might not. RenderingContexts may come from the same window or they might not. Each RenderingContext would have its own WebRender state and image and font uploads would be managed properly.

Requirements:

• The structure of the renderer is appropriate for multiple RenderingContext painters.
  • compositing: Split out Painter from IOCompositor #40264
  • compositor: Rename RenderingGroupId to PainterId #40307
  • compositing: Support per-Painter operations and message handling #40788
  • compositing: Drop Painters when they have no WebViews #41144
• New frames messages are processed per-RenderingContext and only WebViews with that RenderingContext are notified.
  • compositor: Make new frame notifications per Painter #40309
• RefreshDrivers are per-RenderingContext and can be shared between them.
• Font and Image uploads and management are processed per-RenderingContext
  • script: Let HTMLCanvasElement manage the ImageKey for canvases #40375
  • net: Associate every ImageCache with a WebView #40376
• WebGL/WebGPU/etc are run per-RenderingContext
  • compositing: Allow WebGL contexts to have different Surfman devices #40594
  • compositing: Rework WebRender external image handlers to be per-Painter #40690
  • compositor: Share the WebGpuExternalImageMap among all Painters #40737
• WebViewBuilder should take a RenderingContext to specify where it renders  #13995
  • libservo: Have WebView take a RenderingContext rather than Servo #40794