Check when trust agents do not declare a settings activity.

Trust agents are allowed to optionally specify a settings Activity in the
meta-data file. This CL fixes the logic that parses the file to ensure that a
missing settings activity does cause a NullPointerException.

Bug: 133557168
Test: Registering a trust agent without a settings Activity works
Change-Id: I0736a105fee77032acf2ac4b098717b6d49b4099

services/core/java/com/android/server/trust/TrustManagerService.java

@@ -518,8 +518,11 @@ public class TrustManagerService extends SystemService {
                     agentInfo = mActiveAgents.valueAt(index);
                 }
 
-                boolean directUnlock = resolveInfo.serviceInfo.directBootAware
-                    && agentInfo.settings.canUnlockProfile;
+                boolean directUnlock = false;
+                if (agentInfo.settings != null) {
+                    directUnlock = resolveInfo.serviceInfo.directBootAware
+                        && agentInfo.settings.canUnlockProfile;
+                }
 
                 if (directUnlock) {
                     if (DEBUG) Slog.d(TAG, "refreshAgentList: trustagent " + name