Extend the life of Platform.U2F.* histograms

BUG=b:175781791

Change-Id: I394e68ee56faa340eaff8e84aef992e303257910
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2598524
Auto-Submit: Yi Chou <yich@google.com>
Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: Yi Chou <yich@google.com>
Cr-Commit-Position: refs/heads/master@{#839702}

tools/metrics/histograms/histograms_xml/platform/histograms.xml

@@ -1223,14 +1223,14 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="Platform.U2F.Command" enum="Cr50U2FCommands"
-    expires_after="2020-10-07">
+    expires_after="2021-12-21">
   <owner>cylai@chromium.org</owner>
   <owner>cros-hwsec-userland-eng+uma@chromium.org</owner>
   <summary>Records occurrences of U2F commands sent to cr50.</summary>
 </histogram>
 
 <histogram name="Platform.U2F.LegacyCommand" enum="Cr50U2FCommands"
-    expires_after="2020-10-07">
+    expires_after="2021-12-21">
   <owner>cylai@chromium.org</owner>
   <owner>cros-hwsec-userland-eng+uma@chromium.org</owner>
   <summary>Records occurrences of legacy U2F commands sent to cr50.</summary>