Currently SurfaceLayerBridge contains a lot of OffscreenCanvas-specific code. 
But this CL https://chromium-review.googlesource.com/c/chromium/src/+/592398 has introduced
src/third_party/WebKit/Source/platform/exported/WebSurfaceLayerBridge.cpp
which defines 

std::unique_ptr<WebSurfaceLayerBridge> WebSurfaceLayerBridge::Create(
    WebLayerTreeView* layer_tree_view,
    WebSurfaceLayerBridgeObserver* observer) {
  return std::make_unique<SurfaceLayerBridge>(layer_tree_view, observer);
}

and use it in src/content/renderer/media/media_factory.cc

This call to SurfaceLayerBridge's constructor (which is essentially setting up OffscreenCanvasProvider in display compositor) in media factory is wrong. We should correct this back to make SurfaceLayerBridge used only in OffscreenCanvas.

However, we should keep the WebSurfaceLayerBridge, an abstract class, in place; and it could be used in video submission work or other places as needed.