I added an XHR to test_buffered.html, but that has a nasty and unforeseen side effect; the necko cache will cache the request's response, and return it when ChannelMediaResource requests the same resource later. It returns the cached response code (200) too, meaning that we assume that the stream is unseekable. This causes an intermittent timeout in test_bug495300.html on seek.ogv. Once we decide the channel is unseekable there's a data race between the channel/necko filling the media cache and the test running. Once the test starts, the test seeks the <video> to its end/duration. If the MediaCache entry for that video hasn't filled yet, the ogg file will try to seek to the duration, but since the transport is considered unseekable we'll trim the seek target to be within the HTMLMediaElement.seekable ranges. So since the resource isn't fully buffered, we'll trim the seek target, and end up seeking half way through the resource. The test is waiting on an ended event, and since we're not playing we won't ever reach the end, so the test times out. I filed a bug 977314 in necko to see if we can get the cache/necko/something to handle this whole situation better. In the meantime, we should always do a 0- byte range request in all XHR in the media mochitests, so that the necko cache doesn't trip us up!

Do 0- Byte Range Requests in all XHR in media mochitests, so the necko cache behaviour doesn't mess with us. This is a "temporary" measure until a proper necko fix can occur.

I think it'd be better to serve the files we care about not being cached with "Cache-Control: no-store". We should be able to do that via the special ^foo^ files.

Set Cache-Control: no-store for all the files we care about.

Comment on attachment 8382704 [details] [diff] [review] Patch v2: set cache-control: no-store Add the rest of the ^headers^ files to mochitest.ini. :-)

Chris, Cache-control: no-store means to just keep the entries in memory. Did you want to use no-cache to make Necko check with the server (i.e. do the request again) every time?

Hm.. no-store will make the response non-resumable. So it is probably what you want.