[ash-md] Wired in the Shelf color to be derived from the Wallpaper.

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 5ad28349ddb4bac0c389388f2096240c8b51eed6..bd39808b5abfdc9da5f140607dfe4320a7fe8d4a 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -2140,6 +2140,15 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Ash.Wallpaper.TimeSpentExtractingColors" units="ms">
+  <owner>bruthig@chromium.org</owner>
+  <owner>tbuckley@chromium.org</owner>
+  <summary>
+    The time taken to extract colors from wallpapers. Recorded each time the
+    wallpaper image changes.
+  </summary>
+</histogram>
+
 <histogram name="Ash.Wallpaper.Type" enum="WallpaperType">
   <owner>kuscher@google.com</owner>
   <summary>The wallpaper type. Recorded at user login.</summary>
@@ -97741,6 +97750,7 @@ value.
   <int value="-45074716" label="SystemDownloadManager:disabled"/>
   <int value="-23090520" label="disable-search-button-in-omnibox"/>
   <int value="-22544408" label="enable-video-player-chromecast-support"/>
+  <int value="-16824589" label="ash-shelf-color"/>
   <int value="-13918890" label="disable-download-notification"/>
   <int value="-11260186" label="enable-offline-pages-as-saved-pages"/>
   <int value="-5052940" label="enable-simplified-fullscreen"/>