metrics: extend FileBrowser.CrostiniShareDialog histogram expiry

Bug: 995495
Change-Id: I47972375496ec0a7e44d48ae260817faf73175f4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1833021
Auto-Submit: Julian Watson <juwa@google.com>
Commit-Queue: Alex Ilin <alexilin@chromium.org>
Reviewed-by: Joel Hockey <joelhockey@chromium.org>
Reviewed-by: Alex Ilin <alexilin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#701513}

tools/metrics/histograms/histograms.xml

@@ -47022,7 +47022,7 @@ uploading your change for review.
 </histogram>
 
 <histogram name="FileBrowser.CrostiniShareDialog"
-    enum="FileManagerCrostiniShareDialogType" expires_after="2019-10-01">
+    enum="FileManagerCrostiniShareDialogType" expires_after="2020-10-01">
   <owner>joelhockey@chromium.org</owner>
   <owner>tbuckley@chromium.org</owner>
   <summary>Dialog shown when using crostini app to open a file.</summary>