Extend the expiry of Media Router histograms that are still used

Bug: 1160947
Change-Id: Iecc70cc8de059979bef787512b6bd3d2196d9890
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2600263
Commit-Queue: Takumi Fujimoto <takumif@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Cr-Commit-Position: refs/heads/master@{#839674}

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

@@ -1869,7 +1869,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="Cast.Sender.CastMediaType" enum="MediaContainers"
-    expires_after="2021-02-01">
+    expires_after="2022-02-01">
   <owner>takumif@chromium.org</owner>
   <owner>mfoltz@chromium.org</owner>
   <owner>openscreen-eng@google.com</owner>