Remove navigation_service_unittests, along with the service itself.

mash/webtest/manifest.json

Index: mash/webtest/manifest.json
diff --git a/mash/webtest/manifest.json b/mash/webtest/manifest.json
deleted file mode 100644
index 64c0ac6fe81b21b67cf379b563a817d54f732ab0..0000000000000000000000000000000000000000
--- a/mash/webtest/manifest.json
+++ /dev/null
@@ -1,12 +0,0 @@
-{
-  "name": "webtest",
-  "display_name": "Web Test",
-  "interface_provider_specs": {
-    "service_manager:connector": {
-      "provides": { "mash:launchable": [ "mash::mojom::Launchable" ] },
-      "requires": {
-        "*": [ "app" ]
-      }
-    }
-  }
-}