add scroll test

e2e/ambassador/src/client/scrolls.js

@@ -0,0 +1,20 @@
+import { SCROLL_GET, SCROLL_SET } from '../shared/messages';
+import * as ipc from './ipc';
+
+const get = (tabId) => {
+  return ipc.send({
+    type: SCROLL_GET,
+    tabId,
+  });
+};
+
+const set = (tabId, x, y) => {
+  return ipc.send({
+    type: SCROLL_SET,
+    tabId,
+    x,
+    y,
+  });
+};
+
+export { get, set };