Added UMA metrics for ChromeOS first-run UI.

chrome/browser/chromeos/first_run/first_run.cc

Index: chrome/browser/chromeos/first_run/first_run.cc
diff --git a/chrome/browser/chromeos/first_run/first_run.cc b/chrome/browser/chromeos/first_run/first_run.cc
index 90b132246b159ba16de28819bb322d12cd637a01..20d2db8aab0635d6429ff9fdf7f7affa3489086a 100644
--- a/chrome/browser/chromeos/first_run/first_run.cc
+++ b/chrome/browser/chromeos/first_run/first_run.cc
@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 #include "base/command_line.h"
+#include "base/metrics/histogram.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/chromeos/first_run/first_run_controller.h"
 #include "chrome/browser/chromeos/login/user_manager.h"
@@ -101,6 +102,7 @@ void MaybeLaunchDialogAfterSessionStart() {
 }
 
 void LaunchTutorial() {
+  UMA_HISTOGRAM_COUNTS("CrosFirstRun.TutorialLaunched", 1);
   FirstRunController::Start();
 }