[CrOS MultiDevice] Fix crash when password entered on SL sign-in.

When smart lock is enabled, but the lock screen is disabled on the host,
the smart lock metrics recorder crashes as the user enters their
password.  This is because the case PHONE_NOT_LOCKABLE -- which details
this event -- in the ScreenlockState is not considered in the function
which records these metrics, defaulting in a NOTREACHED().

Bug: 915981
Change-Id: If5a022fcea78e6a46739612e3e101a3eec38a399
Reviewed-on: https://chromium-review.googlesource.com/c/1383201Reviewed-by: Ryan Hansberry <hansberry@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: Regan Hsu <hsuregan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#620017}

chrome/browser/chromeos/login/easy_unlock/easy_unlock_service.cc

@@ -645,6 +645,9 @@ EasyUnlockService::GetSmartUnlockPasswordAuthEvent() const {
       case ScreenlockState::PASSWORD_REAUTH:
         return SmartLockMetricsRecorder::SmartLockAuthEventPasswordState::
             kForcedReauth;
+      case ScreenlockState::PHONE_NOT_LOCKABLE:
+        return SmartLockMetricsRecorder::SmartLockAuthEventPasswordState::
+            kPhoneNotLockable;
       default:
         NOTREACHED();
         return SmartLockMetricsRecorder::SmartLockAuthEventPasswordState::

chromeos/components/proximity_auth/smart_lock_metrics_recorder.h

@@ -72,7 +72,8 @@ class SmartLockMetricsRecorder {
     kPhoneLockedAndRssiTooLow = 15,
     kForcedReauth = 16,
     kRequiredForLogin = 17,
-    kMaxValue = kRequiredForLogin
+    kPhoneNotLockable = 18,
+    kMaxValue = kPhoneNotLockable
   };
 
   static void RecordSmartLockUnlockAuthMethodChoice(

tools/metrics/histograms/enums.xml

@@ -48257,9 +48257,10 @@ Called by update_net_trust_anchors.py.-->
   <int value="12" label="Sign-in failed"/>
   <int value="13" label="Pairing added"/>
   <int value="14" label="No screenlock state handler"/>
-  <int value="15" label="RSSI too low"/>
+  <int value="15" label="Phone locked and RSSI too low"/>
   <int value="16" label="Forced Reauthentication"/>
   <int value="17" label="Required for login"/>
+  <int value="18" label="Phone not lockable"/>
 </enum>
 
 <enum name="SmartLockAuthMethodChoice">