Don't dismiss keyguard when enabling it

Introduced in ag/2664156, dismissing a keyguard when it's being disabled has
also caused it to be shown whenever it's being enabled (or re-enabled, or
calling DPM.setKeyguardDisabled when keyguard is enabled).

This change should stop keyguard randomly popping up.

Bug: 133730775
Test: manual
Change-Id: I49f28714b2d149f13168e7564947aaf09c593117

services/devicepolicy/java/com/android/server/devicepolicy/DevicePolicyManagerService.java

@@ -11018,7 +11018,11 @@ public class DevicePolicyManagerService extends BaseIDevicePolicyManager {
                 return false;
             }
             mLockPatternUtils.setLockScreenDisabled(disabled, userId);
-            mInjector.getIWindowManager().dismissKeyguard(null /* callback */, null /* message */);
+            if (disabled) {
+                mInjector
+                        .getIWindowManager()
+                        .dismissKeyguard(null /* callback */, null /* message */);
+            }
             DevicePolicyEventLogger
                     .createEvent(DevicePolicyEnums.SET_KEYGUARD_DISABLED)
                     .setAdmin(who)