Update expiry of WebController.BackForwardListOutOfSync*

These histograms are still detecting the back/forward list being
out-of-sync with WKWebView's URL, caused by bugs in WebKit.
Once these bugs are no longer detected, we can remove workarounds
and also remove the histograms.

Bug: 1147719
Change-Id: Ib4d661ff430c286332b0564c74c4e5850716638a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2533793Reviewed-by: Brian White <bcwhite@chromium.org>
Commit-Queue: Ali Juma <ajuma@chromium.org>
Cr-Commit-Position: refs/heads/master@{#826931}

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

@@ -16540,8 +16540,9 @@ regressions. -->
 </histogram>
 
 <histogram name="WebController.BackForwardListOutOfSync" enum="BooleanHit"
-    expires_after="2020-12-25">
+    expires_after="2021-12-25">
   <owner>ajuma@chromium.org</owner>
+  <owner>eugenebut@chromium.org</owner>
   <owner>gambard@chromium.org</owner>
   <summary>
     [iOS] Counts the number of time the backForwardList of the WebView gets out
@@ -16551,8 +16552,9 @@ regressions. -->
 </histogram>
 
 <histogram name="WebController.BackForwardListOutOfSyncInProvisionalNavigation"
-    enum="IOSOutOfSyncURLAction" expires_after="2020-12-25">
+    enum="IOSOutOfSyncURLAction" expires_after="2021-12-25">
   <owner>ajuma@chromium.org</owner>
+  <owner>eugenebut@chromium.org</owner>
   <owner>gambard@chromium.org</owner>
   <summary>
     [iOS] Records the action take when the backForwardList of the WebView is out