Extend Expiration Dates of InMemory Timing Histograms

Having these histograms is an important reminder that, on many platforms,
these things take on the order of hundreds of milliseconds shortly after
startup, likely making slow slower as a user is trying to interact with
it.

Bug: 871495
Change-Id: Iab792bb11446a8258865562937b8f8b9b81fe4a1
Reviewed-on: https://chromium-review.googlesource.com/1170132
Commit-Queue: Mark Pearson <mpearson@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Reviewed-by: Siddhartha S <ssid@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582314}

tools/metrics/histograms/histograms.xml

@@ -34524,16 +34524,19 @@ uploading your change for review.
 </histogram>
 
 <histogram name="History.InMemoryURLIndexingTime" units="ms"
-    expires_after="2018-08-30">
+    expires_after="2019-08-30">
   <owner>mpearson@chromium.org</owner>
+  <owner>ssid@chromium.org</owner>
   <summary>
     Time to rebuild in-memory url index from main history database. Recorded
     once shortly after profile open.
   </summary>
 </histogram>
 
-<histogram name="History.InMemoryURLIndexRestoreCacheTime" units="ms">
+<histogram name="History.InMemoryURLIndexRestoreCacheTime" units="ms"
+    expires_after="2019-08-30">
   <owner>mpearson@chromium.org</owner>
+  <owner>ssid@chromium.org</owner>
   <summary>
     Time to restore the in-memory url index from disk cache. Recorded on profile
     open.
@@ -34541,8 +34544,9 @@ uploading your change for review.
 </histogram>
 
 <histogram name="History.InMemoryURLIndexSaveCacheTime" units="ms"
-    expires_after="2018-08-30">
+    expires_after="2019-08-30">
   <owner>mpearson@chromium.org</owner>
+  <owner>ssid@chromium.org</owner>
   <summary>
     Time to write in-memory url index to disk cache. Recorded once shortly after
     profile open (after rebuilding the in-memory url index from history) and