Support Skip-Ad media session action

[jiajiabingcheng]

• Specification title:
  Support Skip-Ad media session action

• Specification or proposal URL (if available):
  https://www.w3.org/TR/mediasession/#dom-mediasessionaction-skipad
  Add new skip-ad media session action w3c/mediasession#203 (comment)

• Explainer URL (if available):
  https://developer.chrome.com/blog/media-updates-in-chrome-73#skipad

• Proposal author(s) (@-mention GitHub accounts):
  @jiajiabingcheng

• Caniuse.com URL (optional):

• Bugzilla URL (optional):

• Mozillians who can provide input (optional):

• WebKit standards-position:
  Support Skip-Ad media session action WebKit/standards-positions#350

[zcorpan]

cc @alastor0325 @padenot

[jyasskin]

https://caniuse.com/?search=skipad says this shipped in Firefox 82.

[saschanaz]

Seems right: https://bugzilla.mozilla.org/show_bug.cgi?id=1582569