[Mac] UMA Metrics for the Default Touch Bar

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 bdbb9a92d6c858069d783d92cd8da3121c16eced..5609e676481ec5fa7e6ccda3cc26ae44e6b903b5 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -10680,6 +10680,11 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="DefaultTouchBar.Metrics" enum="DefaultTouchBarAction">
+  <owner>spqchan@chromium.com</owner>
+  <summary>Tracks the usage of the default touch bar buttons.</summary>
+</histogram>
+
 <histogram name="DesktopIOSPromotion.DismissalReason"
     enum="DesktopIOSPromotionDismissalReason">
   <owner>mrefaat@chromium.org</owner>
@@ -86573,6 +86578,16 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="8" label="DSP set to new engine with no previous value in prefs"/>
 </enum>
 
+<enum name="DefaultTouchBarAction" type="int">
+  <int value="0" label="Back"/>
+  <int value="1" label="Forward"/>
+  <int value="2" label="Stop"/>
+  <int value="3" label="Reload"/>
+  <int value="4" label="Search"/>
+  <int value="5" label="Star"/>
+  <int value="6" label="New Tab"/>
+</enum>
+
 <enum name="DefaultWebClientState" type="int">
   <int value="0" label="Not default">Chrome is not the default web client.</int>
   <int value="1" label="Is default">Chrome is the default web client.</int>