Add a resource fetch algorithm return value

[chrisn]

What is the issue with the HTML Standard?

For context, see w3c/media-source#365.

The resource fetch algorithm is exported from HTML and called from Media Source Extensions. The algorithm includes steps such as

• "Abort this subalgorithm, returning to the resource selection algorithm"
• "Abort the overall resource selection algorithm"

which means it's not returning to the right place when called from MSE's end of stream algorithm.

I suggest changing the resource fetch algorithm to return a flag which can be checked by the calling algorithm to decide whether to abort.

Note that MSE defines extensions to the resource fetch algorithm which also need addressing (issue w3c/media-source#324), but I'd like to treat that as separate for now, and make changes incrementally.

@whatwg/media

[annevk]

Adding a return value sounds reasonable. Are you willing to propose a change?

(It would also be nice to refactor the algorithm so the arguments are explicit variables.)

[chrisn]

Thanks, yes I'm happy to work on this.