Preserve request priorities through service worker

Preserves a request’s original priority when it passes through a service worker. Previously, all requests going through a service worker would get "High" priority. This means render-blocking style sheets would have their priority clamped, while less-important resources would get boosted. The priority of network requests can be seen in the DevTools network tab. Render-blocking resources such as style sheets have "Highest" priority, while resources like async scripts have "Low" priority.

Comments

Last year I landed changes ensuring the priorities higher than "High" were preserved through a Service Worker. This chromestatus entry is mostly for tracking the other half of the changes: preserving priorities lower than "High" when they requests pass through a Service Worker.