Extend the expiry date of Enterprise.PublicSession.ExtensionPermissions

This histogram is still helpful to MGS team because there are many new
users and feature requests recently. The statistical data about
extension permissions can save debug efforts and discover potential
issues when necessary.

Bug: 1088743
Change-Id: Id85b2f86caa49d7a4a7604675ce33053408308db
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2452631Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Commit-Queue: Alexei Svitkine <asvitkine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#814226}

tools/metrics/histograms/histograms_xml/enterprise/histograms.xml

@@ -1086,9 +1086,9 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="Enterprise.PublicSession.ExtensionPermissions"
-    enum="ExtensionPermission3" expires_after="M85">
-  <owner>isandrk@chromium.org</owner>
-  <owner>sduraisamy@chromium.org</owner>
+    enum="ExtensionPermission3" expires_after="2022-03-01">
+  <owner>anqing@chromium.org</owner>
+  <owner>apotapchuk@chromium.org</owner>
   <summary>
     Extensions (and apps) are quite restricted in public sessions for security
     and privacy concerns - some permissions are blocked which means the