Keep the PerformanceMonitor.AverageCPU histogram until M88.

This histogram is used to assess the impact of the
IntensiveWakeUpThrottling experiment.

Bug: 1075553
Change-Id: I8ff08aa7e93799a8507f138d5006e45843e9d575
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2426603
Commit-Queue: François Doray <fdoray@chromium.org>
Auto-Submit: François Doray <fdoray@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#812388}

tools/metrics/histograms/histograms_xml/others/histograms.xml

@@ -9833,8 +9833,10 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="PerformanceMonitor.AverageCPU" units="PercentCPUUsage"
-    expires_after="M85">
+    expires_after="M88">
+  <owner>fdoray@chromium.org</owner>
   <owner>oysteine@chromium.org</owner>
+  <owner>catan-team@chromium.org</owner>
   <summary>
     Average CPU utilization of a process, read out at each two-minute interval.
     The utilization is in the 0-100% range per CPU, which is then summed up.