Add Ash.Wallpaper.{DefaultIndex,Type} to histograms.xml.

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 03f4570c6ff1c7bde6c832ab35f262602fa05f2b..ecba9254429718c8085d8edb8be5215dd7a9042f 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -723,6 +723,11 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="Ash.Wallpaper.Type" enum="WallpaperType">
+  <owner>nkostylev@chromium.org</owner>
+  <summary>The wallpaper type. Recorded at user login.</summary>

[Alexei Svitkine (slow), 2014/08/07 18:36:50]

This histogram exists in the internal version of the histograms.xml file.

If you're adding it here, please also remove it from that version
(http://cs/chrome/histograms.xml)

[Thiemo Nagel, 2014/08/07 18:50:40]

Thanks a lot!  I've been looking for it, without success.  (Why is that not part
of the src-internal checkout?)
 
Ok, will do.  Shall I add it first or remove it first?

+</histogram>
+
 <histogram name="Ash.WindowCycleController.CycleTime" units="milliseconds">
   <owner>flackr@chromium.org</owner>
   <owner>kuscher@google.com</owner>
@@ -49602,6 +49607,15 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <int value="11" label="Require phone number"/>
 </enum>
 
+<enum name="WallpaperType" type="int">
+  <int value="0" label="Daily (unused)"/>
+  <int value="1" label="Customized"/>
+  <int value="2" label="Default"/>
+  <int value="3" label="Unknown (unused)"/>
+  <int value="4" label="Online"/>
+  <int value="5" label="Policy"/>
+</enum>
+
 <enum name="WebFontCacheHit" type="int">
   <int value="0" label="Miss"/>
   <int value="1" label="Hit"/>