Change Stability.Internals.SystemCrashCount owner

This change makes davidbienvenu@ and jessemckenna@ the owners of
histogram Stability.Internals.SystemCrashCount, and extends its
expiration date.

Bug: 1123582

Change-Id: Id1c825dd42ee896141817a697c781d975d6b82e6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2485833Reviewed-by: Brian White <bcwhite@chromium.org>
Reviewed-by: Sigurður Ásgeirsson <siggi@chromium.org>
Commit-Queue: Jesse McKenna <jessemckenna@google.com>
Cr-Commit-Position: refs/heads/master@{#818624}

tools/metrics/histograms/histograms_xml/stability/histograms.xml

@@ -301,8 +301,9 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="Stability.Internals.SystemCrashCount" units="crashes"
-    expires_after="2020-10-11">
-  <owner>siggi@chromium.org</owner>
+    expires_after="2021-10-20">
+  <owner>davidbienvenu@chromium.org</owner>
+  <owner>jessemckenna@google.com</owner>
   <summary>
     Number of times a browser crash was detected, where the browser was last
     known to be alive in a Windows system session that terminated abnormally.