Extend some service worker related histograms expiration date

We still want to preserve the following histograms:
* ServiceWorker.InternalsPageAccessed
* ServiceWorker.Storage.DeleteAndStartOverResult

Bug: 1165179
Change-Id: I013479f239444055f312f4ac0c83e2d2469fef89
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2623369
Auto-Submit: Kenichi Ishibashi <bashi@chromium.org>
Commit-Queue: Robert Kaplow <rkaplow@chromium.org>
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842538}

tools/metrics/histograms/histograms_xml/service/histograms.xml

@@ -423,7 +423,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="ServiceWorker.InternalsPageAccessed"
-    enum="ServiceWorkerInternalsLinkQuery" expires_after="M90">
+    enum="ServiceWorkerInternalsLinkQuery" expires_after="M94">
   <owner>bashi@chromium.org</owner>
   <owner>chrome-worker@google.com</owner>
   <summary>
@@ -1080,7 +1080,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="ServiceWorker.Storage.DeleteAndStartOverResult"
-    enum="ServiceWorkerDeleteAndStartOverResult" expires_after="M90">
+    enum="ServiceWorkerDeleteAndStartOverResult" expires_after="M94">
   <owner>bashi@chromium.org</owner>
   <owner>chrome-worker@google.com</owner>
   <summary>