[gnome-shell/wip/laney/systemd-user] Add a systemd unit

[Iain Lane <iainl src gnome org>]

commit 6f5915d3cd3b733ca2888dd3952525aa96eec1ad
Author: Iain Lane <iain orangesquash org uk>
Date:   Wed Jan 17 15:56:17 2018 +0000

    Add a systemd unit
    
    So that we can be started by systemd --user, instead of gnome-session.

 data/gnome-shell.service.in |   12 ++++++++++++
 data/meson.build            |   16 ++++++++++++++++
 meson.build                 |    7 ++++---
 src/meson.build             |    2 +-
 4 files changed, 33 insertions(+), 4 deletions(-)
---
diff --git a/data/gnome-shell.service.in b/data/gnome-shell.service.in
new file mode 100644
index 0000000..0baf24d
--- /dev/null
+++ b/data/gnome-shell.service.in
@@ -0,0 +1,12 @@
+[Unit]
+Description=GNOME Shell
+Wants=gnome-session.service gnome-settings-daemon.target
+After=gnome-session.service gnome-settings-daemon.target graphical-session-pre.target
+PartOf=graphical-session.target
+
+[Service]
+ExecStart=@bindir@/gnome-shell
+Restart=on-failure
+
+[Install]
+RequiredBy=gnome-session.target
diff --git a/data/meson.build b/data/meson.build
index 032e3f0..589d77e 100644
--- a/data/meson.build
+++ b/data/meson.build
@@ -85,6 +85,22 @@ schema = configure_file(
   install_dir: schemadir
 )
 
+unitconf = configuration_data()
+unitconf.set('bindir', bindir)
+
+if have_systemd
+  systemduserunitdir = systemd_dep.get_pkgconfig_variable('systemduserunitdir')
+else
+  systemduserunitdir = join_paths(libdir, 'systemd', 'user')
+endif
+
+unit = configure_file(
+  input: 'gnome-shell.service.in',
+  output: 'gnome-shell.service',
+  configuration: unitconf,
+  install_dir: systemduserunitdir
+)
+
 # for unit tests - gnome.compile_schemas() only looks in srcdir
 custom_target('compile-schemas',
   input: schema,
diff --git a/meson.build b/meson.build
index 988fcb7..64a0389 100644
--- a/meson.build
+++ b/meson.build
@@ -114,10 +114,11 @@ else
 endif
 
 if get_option('systemd')
-  systemd_dep = dependency('libsystemd')
-  have_systemd = systemd_dep.found()
+  libsystemd_dep = dependency('libsystemd')
+  systemd_dep = dependency('systemd')
+  have_systemd = libsystemd_dep.found()
 else
-  systemd_dep = []
+  libsystemd_dep = []
   have_systemd = false
 endif
 
diff --git a/src/meson.build b/src/meson.build
index 3e55573..e082c88 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -54,7 +54,7 @@ gnome_shell_deps = [
   canberra_dep, canberra_gtk_dep,
   polkit_dep,
   gcr_dep,
-  systemd_dep
+  libsystemd_dep
 ]
 
 gnome_shell_deps += nm_deps