UMA for pin unlock success/failure.

chrome/browser/chromeos/login/lock/screen_locker.cc

Index: chrome/browser/chromeos/login/lock/screen_locker.cc
diff --git a/chrome/browser/chromeos/login/lock/screen_locker.cc b/chrome/browser/chromeos/login/lock/screen_locker.cc
index bffe739b0a78a3888c2b5780634e16f315b77887..73b83c91b00da0d5ca51ede1274e9db67e1d7e61 100644
--- a/chrome/browser/chromeos/login/lock/screen_locker.cc
+++ b/chrome/browser/chromeos/login/lock/screen_locker.cc
@@ -189,6 +189,16 @@ void ScreenLocker::OnAuthFailure(const AuthFailure& error) {
     UMA_HISTOGRAM_TIMES("ScreenLocker.AuthenticationFailureTime", delta);
   }
 
+  if (error.IsPinAttempt()) {
+    UMA_HISTOGRAM_ENUMERATION("ScreenLocker.AuthenticationFailure",
+                              UnlockFailure::AUTH_FAILURE_PIN,
+                              UnlockFailure::AUTH_FAILURE_COUNT);
+  } else {
+    UMA_HISTOGRAM_ENUMERATION("ScreenLocker.AuthenticationFailure",
+                              UnlockFailure::AUTH_FAILURE_PASSWORD,
+                              UnlockFailure::AUTH_FAILURE_COUNT);
+  }
+
   EnableInput();
   // Don't enable signout button here as we're showing
   // MessageBubble.
@@ -213,6 +223,16 @@ void ScreenLocker::OnAuthSuccess(const UserContext& user_context) {
     UMA_HISTOGRAM_TIMES("ScreenLocker.AuthenticationSuccessTime", delta);
   }
 
+  if (user_context.IsUsingPin()) {
+    UMA_HISTOGRAM_ENUMERATION("ScreenLocker.AuthenticationSuccess",
+                              int{UnlockSuccess::AUTH_SUCCESS_PIN},

[jdufault, 2016/08/08 18:54:26]

Do you need these casts? You don't have them above.

[sammiequon, 2016/08/09 00:31:25]

Done.

+                              int{UnlockSuccess::AUTH_SUCCESS_COUNT});
+  } else {
+    UMA_HISTOGRAM_ENUMERATION("ScreenLocker.AuthenticationSuccess",
+                              int{UnlockSuccess::AUTH_SUCCESS_PASSWORD},
+                              int{UnlockSuccess::AUTH_SUCCESS_COUNT});
+  }
+
   const user_manager::User* user =
       user_manager::UserManager::Get()->FindUser(user_context.GetAccountId());
   if (user) {