Bug 177579 – Include "beacon" ResourceTiming entry

• Status: NEW
• Component: Page Loading

[Joseph Pecoraro]

Include "beacon" ResourceTiming entry.

The current Resource Timing spec expects beacon resource loads:
https://w3c.github.io/resource-timing/

Spec text:

> On getting, the initiatorType attribute must return one of the following DOMString values:
> ...
>     "beacon", if the request is the result of processing the sendBeacon method [Beacon];

Test:
1. Load https://tests.caniuse.com/?feat=beacon
2. Wait a while so beacons could be fulfilled
3. js> performance.getEntriesByType("resource")
  => No "beacon" entries

Notes:
- No other browser I tested included beacon loads in Resource Timing
- Note adding entries to the performance timeline exposes when the beacon was sent / response received. I don't think thats a bad thing.

[Anne van Kesteren]

I filed https://github.com/w3c/resource-timing/issues/377 to track this.