Merge changes Id88e30f2,I9133556e

* changes:
  Document that changing allowedEmails may cause issues in code owner configs
  Extract FAQs from setup guide to own documentation page

ui/code-owners-service.js

diff --git a/ui/code-owners-service.js b/ui/code-owners-service.js
index 8bb14d1..cf9f1f5 100644
--- a/ui/code-owners-service.js
+++ b/ui/code-owners-service.js
@@ -277,7 +277,11 @@
     try {
       const owners = await this.codeOwnerApi.listOwnersForPath(changeId,
           filePath);
-      this._fetchedOwners.get(filePath).owners = new Set(owners);
+      // In the upcoming backend changes, the api will return an object instead
+      // of array. While this transition is in progress, the frontend supports
+      // both API - the old one and the new one.
+      this._fetchedOwners.get(filePath).owners = new Set(
+          owners instanceof Array ? owners : owners.code_owners);
     } catch (e) {
       this._fetchedOwners.get(filePath).error = e;
     }