Make views_mus_unittests use a static manifest

ui/views/mus/unittests_manifest.json

Index: ui/views/mus/unittests_manifest.json
diff --git a/ui/views/mus/unittests_manifest.json b/ui/views/mus/unittests_manifest.json
new file mode 100644
index 0000000000000000000000000000000000000000..9ba319219c79ef2bd68bd9d2b985540fb2f751ff
--- /dev/null
+++ b/ui/views/mus/unittests_manifest.json
@@ -0,0 +1,11 @@
+{
+  "manifest_version":  1,
+  "name": "mojo:views_mus_unittests",
+  "display_name": "Views Mus Unittests",
+  "capabilities": {
+    "required": {
+      "mojo:desktop_wm": { "interfaces": [ "*" ] },
+      "mojo:mus": { "interfaces": [ "*" ] }
+    }
+  }
+}