Extend a Launcher histogram expiry date.

Bug:1149452

Change-Id: If2defff6b2e1274a22b354e6d1563f77ec1c3004
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2577996Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: Jenny Zhang <jennyz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#834827}

tools/metrics/histograms/histograms_xml/apps/histograms.xml

@@ -1014,7 +1014,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="Apps.AppListSearchOmniboxResultOpenType"
-    enum="AppListOmniboxResult" expires_after="2020-12-31">
+    enum="AppListOmniboxResult" expires_after="2021-12-31">
   <owner>jennyz@chromium.org</owner>
   <owner>newcomer@chromium.org</owner>
   <owner>mpearson@chromium.org</owner>