UMA for pin unlock success/failure.

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

Index: chrome/browser/chromeos/login/lock/screen_locker.h
diff --git a/chrome/browser/chromeos/login/lock/screen_locker.h b/chrome/browser/chromeos/login/lock/screen_locker.h
index 856162047e922dc4e36fb28e303bbc31459e5e23..54529d1b0579f724ee64d747d4642d27857cc40b 100644
--- a/chrome/browser/chromeos/login/lock/screen_locker.h
+++ b/chrome/browser/chromeos/login/lock/screen_locker.h
@@ -131,6 +131,8 @@ class ScreenLocker : public AuthStatusConsumer {
   friend class test::WebUIScreenLockerTester;
   friend class ScreenLockerDelegate;
 
+  enum UnlockType { AUTH_PASSWORD = 0, AUTH_PIN, AUTH_COUNT };

[jdufault, 2016/08/18 17:48:50]

There's a semi-standard comment block that is put on enums used in UMA warning
readers not to modify order/etc. Can you add it here as well?

+
   struct AuthenticationParametersCapture {
     UserContext user_context;
   };
@@ -167,23 +169,26 @@ class ScreenLocker : public AuthStatusConsumer {
   // True if the screen is locked, or false otherwise.  This changes
   // from false to true, but will never change from true to
   // false. Instead, ScreenLocker object gets deleted when unlocked.
-  bool locked_;
+  bool locked_ = false;
 
   // Reference to the single instance of the screen locker object.
   // This is used to make sure there is only one screen locker instance.
   static ScreenLocker* screen_locker_;
 
   // The time when the screen locker object is created.
-  base::Time start_time_;
+  base::Time start_time_ = base::Time::Now();
   // The time when the authentication is started.
   base::Time authentication_start_time_;
 
   // Delegate to forward all login status events to.
   // Tests can use this to receive login status events.
-  AuthStatusConsumer* auth_status_consumer_;
+  AuthStatusConsumer* auth_status_consumer_ = nullptr;
 
   // Number of bad login attempts in a row.
-  int incorrect_passwords_count_;
+  int incorrect_passwords_count_ = 0;
+
+  // Whether the last password entered was a pin or not.
+  bool is_pin_attempt_ = false;
 
   // Copy of parameters passed to last call of OnLoginSuccess for usage in
   // UnlockOnLoginSuccess().