[Extensions] Extend histogram's lifetime

This commit moves expire date of the following histogram:
 * Extensions.CorruptPolicyExtensionDetected3

The expire date is now in sync with the expire date of
Extensions.CorruptPolicyExtensionResolved, which is reported as part of
the same flow.

Bug: 11399860
Change-Id: Ic03e3065370bfb6bd2ccfed74d6b4576e7a002aa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2485066
Commit-Queue: Oleg Davydov <burunduk@chromium.org>
Commit-Queue: Alexei Svitkine <asvitkine@chromium.org>
Auto-Submit: Oleg Davydov <burunduk@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#818920}

tools/metrics/histograms/histograms_xml/extensions/histograms.xml

@@ -485,7 +485,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="Extensions.CorruptPolicyExtensionDetected3"
-    enum="ExtensionPolicyReinstallReason" expires_after="2020-11-30">
+    enum="ExtensionPolicyReinstallReason" expires_after="2021-03-28">
   <owner>burunduk@chromium.org</owner>
   <owner>lazyboy@chromium.org</owner>
   <owner>poromov@chromium.org</owner>