Import async-trait crate.

Bug: 164106399
Bug: 158290206
Test: mm
Change-Id: I0c4a491b785134e4ac1d5572e5ff94b8699dc0bc
diff --git a/tests/ui/bare-trait-object.rs b/tests/ui/bare-trait-object.rs
new file mode 100644
index 0000000..afcd6b4
--- /dev/null
+++ b/tests/ui/bare-trait-object.rs
@@ -0,0 +1,15 @@
+#![deny(bare_trait_objects)]
+
+use async_trait::async_trait;
+
+#[async_trait]
+trait Trait {
+    async fn f(&self);
+}
+
+#[async_trait]
+impl Trait for Send + Sync {
+    async fn f(&self) {}
+}
+
+fn main() {}