UMA for pin unlock success/failure.

chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc

Index: chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc
diff --git a/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc b/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc
index 10bfe44c76e23f9319811f26439e9e9f946bcc2c..0d87258b344940546167baa43e11c81046417118 100644
--- a/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc
+++ b/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc
@@ -1059,14 +1059,21 @@ void SigninScreenHandler::UpdateAddButtonStatus() {
 }
 
 void SigninScreenHandler::HandleAuthenticateUser(const AccountId& account_id,
-                                                 const std::string& password) {
+                                                 const std::string& password,
+                                                 bool authenticated_by_pin) {
   if (!delegate_)
     return;
   DCHECK_EQ(account_id.GetUserEmail(),
             gaia::SanitizeEmail(account_id.GetUserEmail()));
+  chromeos::PinStorage* pin_storage =
+    chromeos::PinStorageFactory::GetForAccountId(account_id);
+  DCHECK(pin_storage ||

[jdufault, 2016/08/12 21:57:33]

Thinking about it more, pin_storage should always be valid. Let's split this up
into two DCHECKs.

DCHECK(pin_storage);
DCHECK(authenticated_...);

Is this the formatting given by git cl format?

[sammiequon, 2016/08/16 17:29:09]

Done.

+         (authenticated_by_pin ==
+           pin_storage->IsPinAuthenticationAvailable()));
 
   UserContext user_context(account_id);
   user_context.SetKey(Key(password));
+  user_context.SetIsUsingPin(authenticated_by_pin);
   delegate_->Login(user_context, SigninSpecifics());
 
   HidePinKeyboardIfNeeded(account_id);