Add a helper to handle captive portal logins

Add a small DBus-activated GtkApplication that embeds a WebKitWebView
and implements some minimal logic to see if the login succeeds.
It will try to connect to a custom NM-provided url (the portal login
page), if one exists, or to www.gnome.org in the normal case of
a portal doing redirect.

https://bugzilla.gnome.org/show_bug.cgi?id=704416

data/Makefile.am

@@ -1,6 +1,24 @@
+CLEANFILES =
+
 desktopdir=$(datadir)/applications
 desktop_DATA = gnome-shell.desktop gnome-shell-wayland.desktop  gnome-shell-extension-prefs.desktop
 
+if HAVE_NETWORKMANAGER
+desktop_DATA += org.gnome.Shell.PortalHelper.desktop
+
+servicedir = $(datadir)/dbus-1/services
+service_DATA = org.gnome.Shell.PortalHelper.service
+
+CLEANFILES += \
+	org.gnome.Shell.PortalHelper.service \
+	org.gnome.Shell.PortalHelper.desktop
+
+endif
+
+%.service: %.service.in
+	$(AM_V_GEN) sed -e "s|@libexecdir[@]|$(libexecdir)|" \
+	    $< > $@ || rm $@
+
 # We substitute in bindir so it works as an autostart
 # file when built in a non-system prefix
 %.desktop.in:%.desktop.in.in
@@ -88,9 +106,11 @@ EXTRA_DIST =						\
 	$(menu_DATA)					\
 	$(convert_DATA)					\
 	$(keys_in_files)				\
+	org.gnome.Shell.PortalHelper.desktop.in		\
+	org.gnome.Shell.PortalHelper.service.in		\
 	org.gnome.shell.gschema.xml.in.in
 
-CLEANFILES =						\
+CLEANFILES +=						\
 	gnome-shell.desktop.in				\
 	gnome-shell-wayland.desktop.in			\
 	gnome-shell-extension-prefs.in			\

data/org.gnome.Shell.PortalHelper.desktop.in

@@ -0,0 +1,9 @@
+[Desktop Entry]
+_Name=Captive Portal
+Type=Application
+Exec=gapplication launch org.gnome.Shell.PortalHelper
+DBusActivatable=true
+NoDisplay=true
+Icon=network-workgroup
+StartupNotify=true
+OnlyShowIn=GNOME;

data/org.gnome.Shell.PortalHelper.service.in

@@ -0,0 +1,3 @@
+[D-BUS Service]
+Name=org.gnome.Shell.PortalHelper
+Exec=@libexecdir@/gnome-shell-portal-helper