Update histograms for ChromeOS Uptime metrics.

BUG=chromium:721891

Change-Id: Ief16bef5e035b3a8cc767395cd220938c7cbf329
Reviewed-on: https://chromium-review.googlesource.com/1081428
Commit-Queue: Jonathan Brandmeyer <jbrandmeyer@chromium.org>
Reviewed-by: Mark Pearson <mpearson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#564965}

tools/metrics/histograms/histograms.xml

@@ -102676,7 +102676,24 @@ uploading your change for review.
   </summary>
 </histogram>
 
+<histogram name="Uptime.OtherProcessesTerminatedToChromeExecAfterLogout"
+    units="ms">
+  <owner>hajimehoshi@chromium.org</owner>
+  <owner>kouhei@chromium.org</owner>
+  <summary>
+    Measures the time elapsed on Chrome OS between when all user-associated
+    processes have been terminated during the logout process and when Chrome is
+    started again to show the login screen.  Since at least ChromeOS M62,
+    equivalent to Uptime.XTerminatedToChromeExecAfterLogout.
+  </summary>
+</histogram>
+
 <histogram name="Uptime.ProcessesTerminatedToXTerminatedAfterLogout" units="ms">
+  <obsolete>
+    Deprecated 05/2018 in Issue 721891 with removal of X11.  Replaced by
+    Uptime.OtherProcessesTerminatedToChromeExecAfterLogout in ChromeOS M69.
+    Equal to 0 since at least ChromeOS M62.
+  </obsolete>
   <owner>hajimehoshi@chromium.org</owner>
   <owner>kouhei@chromium.org</owner>
   <summary>
@@ -102699,6 +102716,10 @@ uploading your change for review.
 </histogram>
 
 <histogram name="Uptime.XTerminatedToChromeExecAfterLogout" units="ms">
+  <obsolete>
+    Replaced by Uptime.OtherProcessesTerminatedToChromeExecAfterLogout in
+    ChromeOS M69.  Equivalent to the new name since at least ChromeOS M62.
+  </obsolete>
   <owner>hajimehoshi@chromium.org</owner>
   <owner>kouhei@chromium.org</owner>
   <summary>