ash:Shelf - Added UMA stats for ShelfAlignment

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 d66818d640aea88b091d8fb230c4a9f8321af6e6..bdca5457a78005df58ed38ff71d2715cb2692a87 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -230,6 +230,24 @@ other types of suffix sets.
   </summary>
 </histogram>
 
+<histogram name="Ash.ShelfAlignmentOverTime" enum="ShelfAlignmentValue">
+  <summary>
+    The current state of the shelf (alignment) tracked over time by logging on a
+    regular basis (30 minutes), this is used instead of log in or shelf usage to
+    track users that do not lock/unlock or log in frequently and use a small
+    number of browser instances or otherwise infrequently interact with the
+    shelf launcher.
+  </summary>
+</histogram>
+
+<histogram name="Ash.ShelfAlignmentUsage" enum="ShelfAlignmentValue">
+  <summary>
+    The current state of the shelf (alignment) when the shelf launcher is used
+    to launch an app/window/etc, this is used instead of log in to give data on
+    users that do not lock/unlock or log in frequently.
+  </summary>
+</histogram>
+
 <histogram name="Ash.TouchDuration" units="milliseconds">
   <summary>The duration of a touch-sequence.</summary>
 </histogram>
@@ -27191,6 +27209,15 @@ other types of suffix sets.
   <int value="3" label="Specified URLs"/>
 </enum>
 
+<enum name="ShelfAlignmentValue" type="int">
+  <summary>
+    The alignment of the shelf area (see ash/launcher/launcher_view.cc).
+  </summary>
+  <int value="0" label="Bottom"/>
+  <int value="1" label="Left"/>
+  <int value="2" label="Right"/>
+</enum>
+
 <enum name="ShillTerminationActionResult" type="int">
   <summary>
     The termination action result types come from TerminationActionResult in