Enrollment recovery: Add UMA stats.

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 1374c6a8e1b185e623e53d97f74f13ca3128b708..2bdad209bca30e462eb53c0082b52353a6c052c0 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -5332,6 +5332,11 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="Enterprise.EnrollmentRecovery" enum="EnterpriseEnrollmentType">
+  <owner>tnagel@chromium.org</owner>
+  <summary>Events related to Chrome OS enterprise enrollment recovery.</summary>
+</histogram>
+
 <histogram name="Enterprise.IOSPolicies">
   <owner>joaodasilva@chromium.org</owner>
   <summary>
@@ -37072,6 +37077,10 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <int value="23" label="Domain mismatch">
     Enrollment failed because the device belongs to a different domain.
   </int>
+  <int value="24" label="Triggered">
+    Enrollment has been triggered, the credential screen has been shown.
+  </int>
+  <int value="25" label="Retried">The user retried to submit credentials.</int>
 </enum>
 
 <enum name="EnterprisePolicies" type="int">