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..2b5a0a0727923d89170637ee8e970a42a2c63846 100644
--- a/chrome/browser/chromeos/login/lock/screen_locker.cc
+++ b/chrome/browser/chromeos/login/lock/screen_locker.cc
@@ -189,6 +189,14 @@ void ScreenLocker::OnAuthFailure(const AuthFailure& error) {
     UMA_HISTOGRAM_TIMES("ScreenLocker.AuthenticationFailureTime", delta);
   }
 
+  if (error.IsPinAttempt()) {

[jdufault, 2016/08/04 19:42:04]

This is a lot of plumbing that I think we can do without.

There are four things this logs:
1. PIN success
2. PIN failure
3. Password success
4. Password failure

PIN success and failure can both be done inside of Authenticate[1], since the
PIN check is synchronous. Password success can be done inside of
OnPasswordAuthSuccess[2], which does not get called if PIN was used to unlock
the device. OnAuthFailure already has a metric [3].

1:
https://cs.chromium.org/chromium/src/chrome/browser/chromeos/login/lock/scree...
2:
https://cs.chromium.org/chromium/src/chrome/browser/chromeos/login/lock/scree...
3:
https://cs.chromium.org/chromium/src/chrome/browser/chromeos/login/lock/scree...

[sammiequon, 2016/08/05 01:45:59]

As per our offline chat there may be some issues. OnAuthFailure is reached by
both PIN failure and pwd failure and has no way of differentiating.

+    UMA_HISTOGRAM_ENUMERATION("ScreenLocker.AuthenticationFailure",
+                              AUTH_FAILURE_PIN, AUTH_FAILURE_TYPE_NUM);
+  } else {
+    UMA_HISTOGRAM_ENUMERATION("ScreenLocker.AuthenticationFailure",
+                              AUTH_FAILURE_PASSWORD, AUTH_FAILURE_TYPE_NUM);
+  }
+
   EnableInput();
   // Don't enable signout button here as we're showing
   // MessageBubble.
@@ -213,6 +221,14 @@ void ScreenLocker::OnAuthSuccess(const UserContext& user_context) {
     UMA_HISTOGRAM_TIMES("ScreenLocker.AuthenticationSuccessTime", delta);
   }
 
+  if (user_context.IsUsingPin()) {
+    UMA_HISTOGRAM_ENUMERATION("ScreenLocker.AuthenticationSuccess",
+                              AUTH_SUCCESS_PIN, AUTH_SUCCESS_TYPE_NUM);
+  } else {
+    UMA_HISTOGRAM_ENUMERATION("ScreenLocker.AuthenticationSuccess",
+                              AUTH_SUCCESS_PASSWORD, AUTH_SUCCESS_TYPE_NUM);
+  }
+
   const user_manager::User* user =
       user_manager::UserManager::Get()->FindUser(user_context.GetAccountId());
   if (user) {