Compilation without GStreamer

[chazanov]

As GStreamer is a real hassle I would like to ask for the compilation option to compile without it.

[jdm]

This should be easy to accomplish in a few steps:

• update servo-media to a revision that includes servo/media@a94a3b5 (see ongoing work at Shutdown player when HTMLMediaElement is dropped #22944)
• add a Cargo feature to the auto backend which is used to enable the dummy backend
• add a Cargo feature to the desktop app which plumbs the disable-gstreamer feature down to the crates which depend on servo-media-auto
• add a mach build argument to enable the disable-gstreamer feature

[chazanov]

@jdm Hi Josh, what's the current status? Have you implemented this?

[paulrouget]

This should be easy to accomplish in a few steps

I gave it a try. I'm not sure it's easy, we can't have a feature that "disable" something in Cargo.toml. The rustc feature will work, but something like this in Cargo.toml won't:

[target.'cfg(all(target="android", feature="disable-gstreamer"))'.dependencies]

It's a known limitation of Cargo (see rust-lang/cargo#5499).

So I think we will need an intermediate crate (relevant irc conversation: https://mozilla.logbot.info/servo/20190514#c16308257).

I'm open to any other ideas.

[ghost]

Fixed in #24668