Move expiry of test histograms for more testing.

Change-Id: Iec70e81ccfa00b56cc67c2934ea4df0a9505b0ac
Reviewed-on: https://chromium-review.googlesource.com/1117207Reviewed-by: Ilya Sherman <isherman@chromium.org>
Commit-Queue: Gayane Petrosyan <gayane@chromium.org>
Cr-Commit-Position: refs/heads/master@{#570932}

tools/metrics/histograms/histograms.xml

@@ -103051,25 +103051,25 @@ uploading your change for review.
   </summary>
 </histogram>
 
-<histogram name="UMA.ExpiredHistogram.BugReportTest" expires_after="2018-05-01">
+<histogram name="UMA.ExpiredHistogram.BugReportTest" expires_after="2018-07-20">
   <owner>gayane@chromium.org</owner>
   <summary>Not logged. Used for testing histogram expiry checker.</summary>
 </histogram>
 
 <histogram name="UMA.ExpiredHistogram.Milestone.BugReportTest"
-    expires_after="M67">
+    expires_after="M68">
   <owner>gayane@chromium.org</owner>
   <summary>Not logged. Used for testing histogram expiry checker.</summary>
 </histogram>
 
 <histogram name="UMA.ExpiredHistogram.Milestone.Soon.BugReportTest"
-    expires_after="M68">
+    expires_after="M69">
   <owner>gayane@chromium.org</owner>
   <summary>Not logged. Used for testing histogram expiry checker.</summary>
 </histogram>
 
 <histogram name="UMA.ExpiredHistogram.Soon.BugReportTest"
-    expires_after="2018-06-01">
+    expires_after="2018-08-01">
   <owner>gayane@chromium.org</owner>
   <summary>Not logged. Used for testing histogram expiry checker.</summary>
 </histogram>