Right now PipeWire is enabled when Wayland session is enabled regardless of active Gtk backend (X11/Wayland).

Let's use PipeWire only when Wayland Gtk backend is used and disable it when X11 display is used to avoid possible regressions.

Right now PipeWire is enabled when Wayland session is used regardless of an active Gtk backend (X11/Wayland).
Let's use PipeWire only when Wayland Gtk backend is used and disable it for X11 one to avoid possible regressions.

Backed out for causing linux bustages

Backout link: https://hg.mozilla.org/integration/autoland/rev/cf1fe9971e5f902b3a1aa62dcec5367f7dc570a1

Push with failures: https://treeherder.mozilla.org/jobs?repo=autoland&resultStatus=testfailed%2Cbusted%2Cexception%2Crunnable&revision=fc296ca6ed9c1a10b72bbbe55585ed2118242134

Failure log: https://treeherder.mozilla.org/logviewer?job_id=320799970&repo=autoland&lineNumber=69965

"WARNING - [style 0.0.1] Warning: can't set binop_separator = Back, unstable features are only available in nightly channel.
[task 2020-11-05T08:09:52.624Z] 08:09:52 WARNING - [style 0.0.1] Warning: can't set match_block_trailing_comma = true, unstable features are only available in nightly channel.
[task 2020-11-05T08:09:52.624Z] 08:09:52 INFO - Compiling fxa-client v0.1.0 (https://github.com/mozilla/application-services?rev=1c4dd52e61324eb124ba41cfbb56dcbc6b930d9f#1c4dd52e)
[task 2020-11-05T08:09:52.627Z] 08:09:52 INFO - Running CARGO=/builds/worker/fetches/rustc/bin/cargo CARGO_MANIFEST_DIR=/builds/worker/checkouts/gecko/third_party/rust/fxa-client CARGO_PKG_AUTHORS='Edouard Oger <eoger@fastmail.com>' CARGO_PKG_DESCRIPTION= CARGO_PKG_HOMEPAGE= CARGO_PKG_NAME=fxa-client CARGO_PKG_REPOSITORY= CARGO_PKG_VERSION=0.1.0 CARGO_PKG_VERSION_MAJOR=0 CARGO_PKG_VERSION_MINOR=1 CARGO_PKG_VERSION_PATCH=0 CARGO_PKG_VERSION_PRE= LD_LIBRARY_PATH='/builds/worker/workspace/obj-build/debug/deps:/builds/worker/fetches/rustc/lib:/builds/worker/workspace/obj-build/dist/bin:/builds/worker/fetches/gcc/lib64:/builds/worker/fetches/gcc/lib32:/builds/worker/fetches/gcc/lib' /builds/worker/fetches/sccache/sccache /builds/worker/fetches/rustc/bin/rustc --crate-name fxa_client --edition=2018 /builds/worker/checkouts/gecko/third_party/rust/fxa-client/src/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts --crate-type lib --emit=dep-info,metadata,link -C opt-level=1 -C panic=abort -C debuginfo=2 -C debug-assertions=on --cfg 'feature="default"' --cfg 'feature="gecko"' -C metadata=0e20d7fb45ede2dc -C extra-filename=-0e20d7fb45ede2dc --out-dir /builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps --target x86_64-unknown-linux-gnu -C linker=/builds/worker/checkouts/gecko/build/cargo-linker -L dependency=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps -L dependency=/builds/worker/workspace/obj-build/debug/deps --extern anyhow=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/libanyhow-0fe20c3c4d7018fc.rmeta --extern base64=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/libbase64-dc3fd5d11f30f837.rmeta --extern error_support=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/liberror_support-8ad2ac638475579e.rmeta --extern ffi_support=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/libffi_support-d1f4b3862ed02aee.rmeta --extern hex=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/libhex-72a2c610e0cde68e.rmeta --extern jwcrypto=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/libjwcrypto-ed3dab9788dab2e1.rmeta --extern lazy_static=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/liblazy_static-bb4de943aa03b5c6.rmeta --extern log=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/liblog-7fee9b05e7ad7e60.rmeta --extern prost=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/libprost-157d653401e18e05.rmeta --extern prost_derive=/builds/worker/workspace/obj-build/debug/deps/libprost_derive-2f453c0b519b5e6a.so --extern rand_rccrypto=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/librand_rccrypto-0027c7aadd7c858f.rmeta --extern rc_crypto=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/librc_crypto-853bdcb174b0a4ac.rmeta --extern serde=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/libserde-3fe387c1918e0335.rmeta --extern serde_derive=/builds/worker/workspace/obj-build/debug/deps/libserde_derive-846fd224bf9d2aed.so --extern serde_json=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/libserde_json-c5382b9c16f9f9f0.rmeta --extern sync_guid=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/libsync_guid-9e72a134f55ccd8d.rmeta --extern sync15=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/libsync15-d5f468e5296edfd9.rmeta --extern thiserror=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/libthiserror-60164b30be09ac30.rmeta --extern url=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/liburl-764a3ac1e7167f0a.rmeta --extern viaduct=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/libviaduct-a9c3c8641002822e.rmeta --cap-lints warn -C opt-level=2 -C debuginfo=2 -C force-frame-pointers=yes -Dwarnings -C codegen-units=1
[task 2020-11-05T08:09:52.627Z] 08:09:52 ERROR - error[E0658]: use of unstable library feature 'str_strip': newly added
[task 2020-11-05T08:09:52.627Z] 08:09:52 INFO - --> /builds/worker/checkouts/gecko/third_party/rust/fxa-client/src/config.rs:82:41
[task 2020-11-05T08:09:52.627Z] 08:09:52 INFO - |
[task 2020-11-05T08:09:52.628Z] 08:09:52 INFO - 82 | match token_server_url_override.strip_suffix("/1.0/sync/1.5") {
[task 2020-11-05T08:09:52.628Z] 08:09:52 INFO - | ^^^^^^^^^^^^
[task 2020-11-05T08:09:52.628Z] 08:09:52 INFO - |
[task 2020-11-05T08:09:52.628Z] 08:09:52 INFO - = note: see issue #67302 https://github.com/rust-lang/rust/issues/67302 for more information
[task 2020-11-05T08:09:52.628Z] 08:09:52 ERROR - error: aborting due to previous error
[task 2020-11-05T08:09:52.628Z] 08:09:52 INFO - For more information about this error, try rustc --explain E0658.
[task 2020-11-05T08:09:52.628Z] 08:09:52 INFO - error: could not compile fxa-client.
[task 2020-11-05T08:09:52.628Z] 08:09:52 INFO - Caused by:
[task 2020-11-05T08:09:52.631Z] 08:09:52 INFO - process didn't exit successfully: CARGO=/builds/worker/fetches/rustc/bin/cargo CARGO_MANIFEST_DIR=/builds/worker/checkouts/gecko/third_party/rust/fxa-client CARGO_PKG_AUTHORS='Edouard Oger <eoger@fastmail.com>' CARGO_PKG_DESCRIPTION= CARGO_PKG_HOMEPAGE= CARGO_PKG_NAME=fxa-client CARGO_PKG_REPOSITORY= CARGO_PKG_VERSION=0.1.0 CARGO_PKG_VERSION_MAJOR=0 CARGO_PKG_VERSION_MINOR=1 CARGO_PKG_VERSION_PATCH=0 CARGO_PKG_VERSION_PRE= LD_LIBRARY_PATH='/builds/worker/workspace/obj-build/debug/deps:/builds/worker/fetches/rustc/lib:/builds/worker/workspace/obj-build/dist/bin:/builds/worker/fetches/gcc/lib64:/builds/worker/fetches/gcc/lib32:/builds/worker/fetches/gcc/lib' /builds/worker/fetches/sccache/sccache /builds/worker/fetches/rustc/bin/rustc --crate-name fxa_client --edition=2018 /builds/worker/checkouts/gecko/third_party/rust/fxa-client/src/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts --crate-type lib --emit=dep-info,metadata,link -C opt-level=1 -C panic=abort -C debuginfo=2 -C debug-assertions=on --cfg 'feature="default"' --cfg 'feature="gecko"' -C metadata=0e20d7fb45ede2dc -C extra-filename=-0e20d7fb45ede2dc --out-dir /builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps --target x86_64-unknown-linux-gnu -C linker=/builds/worker/checkouts/gecko/build/cargo-linker -L dependency=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps -L dependency=/builds/worker/workspace/obj-build/debug/deps --extern anyhow=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/libanyhow-0fe20c3c4d7018fc.rmeta --extern base64=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/libbase64-dc3fd5d11f30f837.rmeta --extern error_support=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/liberror_support-8ad2ac638475579e.rmeta --extern ffi_support=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/libffi_support-d1f4b3862ed02aee.rmeta --extern hex=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/libhex-72a2c610e0cde68e.rmeta --extern jwcrypto=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/libjwcrypto-ed3dab9788dab2e1.rmeta --extern lazy_static=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/liblazy_static-bb4de943aa03b5c6.rmeta --extern log=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/liblog-7fee9b05e7ad7e60.rmeta --extern prost=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/libprost-157d653401e18e05.rmeta --extern prost_derive=/builds/worker/workspace/obj-build/debug/deps/libprost_derive-2f453c0b519b5e6a.so --extern rand_rccrypto=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/librand_rccrypto-0027c7aadd7c858f.rmeta --extern rc_crypto=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/librc_crypto-853bdcb174b0a4ac.rmeta --extern serde=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/libserde-3fe387c1918e0335.rmeta --extern serde_derive=/builds/worker/workspace/obj-build/debug/deps/libserde_derive-846fd224bf9d2aed.so --extern serde_json=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/libserde_json-c5382b9c16f9f9f0.rmeta --extern sync_guid=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/libsync_guid-9e72a134f55ccd8d.rmeta --extern sync15=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/libsync15-d5f468e5296edfd9.rmeta --extern thiserror=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/libthiserror-60164b30be09ac30.rmeta --extern url=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/liburl-764a3ac1e7167f0a.rmeta --extern viaduct=/builds/worker/workspace/obj-build/x86_64-unknown-linux-gnu/debug/deps/libviaduct-a9c3c8641002822e.rmeta --cap-lints warn -C opt-level=2 -C debuginfo=2 -C force-frame-pointers=yes -Dwarnings -C codegen-units=1 (exit code: 1)
[task 2020-11-05T08:09:52.631Z] 08:09:52 INFO - warning: build failed, waiting for other jobs to finish..."

Relanded the patch, the failures were actually caused by bug 1675190 and were fixed by the following backout: https://hg.mozilla.org/integration/autoland/rev/4cb5c0af79d689a8b399fc3b769040ad3da4e245

https://hg.mozilla.org/mozilla-central/rev/1c126b520042