Add metadata files for plotters-backend.

Bug: 155309706
Change-Id: I9ed92a4fc069887f95c7da1b443bf5aa23c95918
diff --git a/Android.bp b/Android.bp
new file mode 100644
index 0000000..b5f1a77
--- /dev/null
+++ b/Android.bp
@@ -0,0 +1,10 @@
+// This file is generated by cargo2android.py --run --device --dependencies.
+// Do not modify this file as changes will be overridden on upgrade.
+
+rust_library {
+    name: "libplotters_backend",
+    host_supported: true,
+    crate_name: "plotters_backend",
+    srcs: ["src/lib.rs"],
+    edition: "2018",
+}