Linux: Remove --wm-user-time-ms command line argument

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index c9707ba406d2d7c74f16ce5e3dc00e5a1b32ef20..367f2ef9d9594806f6a95677f635d7e5eac85d30 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -13483,6 +13483,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 
 <histogram name="Event.Latency.X11EventSource.UpdateServerTime"
     units="microseconds">
+  <obsolete>
+    Deprecated 08/2016, and replaced by Linux.X11.ServerRTT.
+  </obsolete>
   <owner>thomasanderson@chromium.org</owner>
   <summary>Time to request a timestamp from the X server.</summary>
 </histogram>
@@ -21315,6 +21318,14 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Linux.X11.ServerRTT" units="microseconds">
+  <owner>thomasanderson@chromium.org</owner>
+  <summary>
+    RTT between Chrome and the X11 server.  Tracked in X11EventSource by
+    measuring the latency to receive a property event after changing a property.
+  </summary>
+</histogram>
+
 <histogram name="LocalDiscovery.ClientRestartAttempts">
   <owner>noamsml@chromium.org</owner>
   <owner>vitalybuka@chromium.org</owner>