Checking user understanding of shared identity

Add IEE role in surveys of users to check that they understand
common identity.

(It would be impractical to leave this to the browser and site
author, especially in cases where the browser and site author
have a business relationship that would be influenced by FPS
validity or invalidity.)

Refs WICG#43 WICG#48 WICG#64 WICG#76

ua_policy_proposal.md

@@ -59,7 +59,7 @@ For each element of the First Party Set policy, we propose an enforcement method
 <tr>
 <td>A group identity that is easily discoverable by a users </td>
 <td>UI treatment (and co-branding in some cases)<sup>2</sup> </td>
-<td>None (solely the browser's and site author's responsibility)</td>
+<td>Conduct user surveys to determine if common identity is understandable to users</td>
 </tr>
 <tr>
 <td>Common Privacy Policy </td>