Enrollment recovery: Add UMA stats.

chrome/browser/chromeos/login/enrollment/enrollment_screen_actor.h

Index: chrome/browser/chromeos/login/enrollment/enrollment_screen_actor.h
diff --git a/chrome/browser/chromeos/login/enrollment/enrollment_screen_actor.h b/chrome/browser/chromeos/login/enrollment/enrollment_screen_actor.h
index 84a4863890180d9cb127d3754244527312b18add..74f4ffe9c985587e9f0489688df9a2ccb084bbfe 100644
--- a/chrome/browser/chromeos/login/enrollment/enrollment_screen_actor.h
+++ b/chrome/browser/chromeos/login/enrollment/enrollment_screen_actor.h
@@ -29,11 +29,14 @@ class EnrollmentScreenActor {
     UI_ERROR_FATAL,
   };
 
-  // Describes the enrollment mode.
+  // Describes the enrollment mode.  Must be kept in sync with
+  // |kEnrollmentModes| in enrollment_screen_handler.cc.
   enum EnrollmentMode {
-    ENROLLMENT_MODE_MANUAL,  // Manually triggered enrollment.
-    ENROLLMENT_MODE_FORCED,  // Forced enrollment, user can't skip.
-    ENROLLMENT_MODE_AUTO,    // Auto-enrollment during first sign-in.
+    ENROLLMENT_MODE_MANUAL,    // Manually triggered enrollment.
+    ENROLLMENT_MODE_FORCED,    // Forced enrollment, user can't skip.
+    ENROLLMENT_MODE_AUTO,      // Auto-enrollment during first sign-in.
+    ENROLLMENT_MODE_RECOVERY,  // Recover from "spontaneous unenrollment".
+    ENROLLMENT_MODE_COUNT      // Counter must be last. Not an enrollment mode.
   };
 
   // This defines the interface for controllers which will be called back when