Add metrics to printer setup flow.

chrome/browser/chromeos/printing/printer_configurer.h

Index: chrome/browser/chromeos/printing/printer_configurer.h
diff --git a/chrome/browser/chromeos/printing/printer_configurer.h b/chrome/browser/chromeos/printing/printer_configurer.h
index 0d540c07a1861d4365be997b1d0dda542ff5b45b..e89f6d3671b75f71d2828113bdb784b3d1afe46c 100644
--- a/chrome/browser/chromeos/printing/printer_configurer.h
+++ b/chrome/browser/chromeos/printing/printer_configurer.h
@@ -14,6 +14,8 @@ class Profile;
 
 namespace chromeos {
 
+// These values are written to logs.  New enum values can be added, but existing
+// enums must never be renumbered or deleted and reused.
 enum PrinterSetupResult {
   kFatalError = 0,          // Setup failed in an unrecognized way
   kSuccess = 1,             // Printer set up successfully