Expose ashpd's tokio support

Cargo.toml

@@ -15,6 +15,10 @@ default = ["gtk3"]
 file-handle-inner = []
 gtk3 = ["gtk-sys", "glib-sys", "gobject-sys"]
 xdg-portal = ["ashpd", "urlencoding", "pollster"]
+# Use async-std for xdg-portal
+async-std = ["ashpd?/async-std"]
+# Use tokio for xdg-portal
+tokio = ["ashpd?/tokio"]
 common-controls-v6 = ["windows-sys/Win32_UI_Controls"]
 
 [dev-dependencies]
@@ -42,7 +46,7 @@ windows-sys = { version = "0.48", features = [
 
 [target.'cfg(any(target_os = "linux", target_os = "freebsd", target_os = "dragonfly", target_os = "netbsd", target_os = "openbsd"))'.dependencies]
 # XDG Desktop Portal
-ashpd = { version = "0.6", optional = true }
+ashpd = { version = "0.6", optional = true, default-features = false }
 urlencoding = { version = "2.1.0", optional = true }
 pollster = { version = "0.3", optional = true }
 # GTK

src/lib.rs

@@ -55,7 +55,7 @@
 //!
 //! ## XDG Desktop Portal backend
 //! The XDG Desktop Portal backend is used when the `gtk3` feature is disabled with
-//! [`default-features = false`](https://doc.rust-lang.org/cargo/reference/features.html#dependency-features), and `xdg-portal` is enabled instead. This backend will use either the GTK or KDE file dialog depending on the desktop environment
+//! [`default-features = false`](https://doc.rust-lang.org/cargo/reference/features.html#dependency-features), and `xdg-portal` is enabled instead. Either the `tokio` or `async-std` feature must be enabled. This backend will use either the GTK or KDE file dialog depending on the desktop environment
 //! in use at runtime. It does not have any non-Rust
 //! build dependencies, however it requires the user to have either the
 //! [GTK](https://github.com/flatpak/xdg-desktop-portal-gtk),