[CrOS] Postpone expiration of LoadTimeViewsBased histogram

Bug: 1152041
Change-Id: I040b4d71be130b0a0102e66a13976c3a940123eb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2560102Reviewed-by: Roman Sorokin [CET] <rsorokin@chromium.org>
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Commit-Queue: Thomas Tellier <tellier@google.com>
Cr-Commit-Position: refs/heads/master@{#831011}

tools/metrics/histograms/histograms_xml/chromeos/histograms.xml

@@ -1176,7 +1176,7 @@ incoming reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="ChromeOS.UserAddingScreen.LoadTimeViewsBased" units="ms"
-    expires_after="2021-01-07">
+    expires_after="2021-05-16">
   <owner>tellier@google.com</owner>
   <owner>rsorokin@chromium.org</owner>
   <owner>cros-oac@google.com</owner>