Extracting more than one wallpaper prominent color

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 78a757d7251b25850c11d988425f1852ccb3ed1e..a8622fbf0205e07c835e965d45de3075dbf79f71 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -2529,7 +2529,7 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <owner>tbuckley@chromium.org</owner>
   <summary>
     The time taken to extract colors from wallpapers. Recorded each time the
-    wallpaper image changes.
+    wallpaper image changes. It may contain multiple colors extracted.
   </summary>
 </histogram>
 
@@ -2540,16 +2540,17 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
     The time taken to extract colors from 'expensive' wallpapers. Recorded each
     time the wallpaper image changes and the color extraction is expected to be
     expensive, e.g. image size &gt; 100 pixels. This includes time spent
-    switching threads.
+    switching threads. It may contain multiple colors extracted.
   </summary>
 </histogram>
 
-<histogram name="Ash.Wallpaper.ColorExtractionResult" enum="BooleanSuccess">
+<histogram name="Ash.Wallpaper.ColorExtractionResult"
+    enum="WallpaperColorExtractionResult">

[Ilya Sherman, 2017/06/20 23:00:00]

Hmm, none of the listed enum options look like a failure.  Since you're changing
the semantics of this histogram, please rename it as well, and mark the old one
as <obsolete>.

[Qiang(Joe) Xu, 2017/06/21 01:10:52]

Done.

   <owner>bruthig@chromium.org</owner>
   <owner>tbuckley@chromium.org</owner>
   <summary>
-    Tracks the success rate for wallpaper color extraction. Recorded each time
-    the wallpaper image changes.
+    Tracks the success rate for each wallpaper color extraction. Recorded each
+    time the wallpaper image changes.
   </summary>
 </histogram>