Update deprecation comment for Download.IOSDownloadedFileStatusCode

Change-Id: Ie1f5033f6d7b6d70ad2f15bf49ad099155becc49
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2586027
Commit-Queue: Eugene But <eugenebut@chromium.org>
Commit-Queue: Caitlin Fischer <caitlinfischer@google.com>
Auto-Submit: Eugene But <eugenebut@chromium.org>
Reviewed-by: Caitlin Fischer <caitlinfischer@google.com>
Cr-Commit-Position: refs/heads/master@{#836194}

tools/metrics/histograms/histograms_xml/download/histograms.xml

@@ -301,9 +301,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 <histogram name="Download.IOSDownloadedFileStatusCode" units="units"
     expires_after="2020-12-08">
   <obsolete>
-    No longer recorded. Unclear when recording code was removed as git log -S
-    Download.IOSDownloadedFileStatusCode did not find anything useful. Marked as
-    obsolete on 12-2020.
+    Deprecated as of 08-2018. Recording code was removed in crrev.com/c/1170128.
   </obsolete>
   <owner>eugenebut@chromium.org</owner>
   <owner>stkhapugin@chromium.org</owner>