Extend SubresourceFilter.PageLoad.ActivationDecision

We're still looking at data from this histogram

Change-Id: Ia1353e2ae5677a2b39ca355593cdc3780d021428
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1690567Reviewed-by: Josh Karlin <jkarlin@chromium.org>
Commit-Queue: Charlie Harrison <csharrison@chromium.org>
Cr-Commit-Position: refs/heads/master@{#675786}

tools/metrics/histograms/histograms.xml

@@ -129951,7 +129951,7 @@ should be kept until we use this API.  -->
 </histogram>
 
 <histogram name="SubresourceFilter.PageLoad.ActivationDecision"
-    enum="SubresourceFilterActivationDecision" expires_after="M77">
+    enum="SubresourceFilterActivationDecision" expires_after="M80">
   <owner>csharrison@chromium.org</owner>
   <summary>
     Records the policy decision to activate subresource filtering for a page