Import 'futures-channel' rust crate version 0.3.4

Bug: b/151760391
Test: m crosvm.experimental
Change-Id: I40daaec86f1c422d2bc563057f04384d4fda7740
diff --git a/METADATA b/METADATA
new file mode 100644
index 0000000..4fcad10
--- /dev/null
+++ b/METADATA
@@ -0,0 +1,17 @@
+name: "futures-channel"
+description:
+    "Channels for asynchronous communication using futures-rs."
+
+third_party {
+  url {
+    type: HOMEPAGE
+    value: "https://crates.io/crates/futures-channel"
+  }
+  url {
+    type: GIT
+    value: "https://github.com/rust-lang/futures-rs"
+  }
+  version: "0.3.4"
+  last_upgrade_date { year: 2020 month: 3 day: 17 }
+  license_type: NOTICE
+}