Add null check for vrManager

If VrManagerService is not started, vrManager will be null. Need
add check for it.

Test: robotests
Bug: 112064298
Change-Id: I899337bb5a996efffe82970fa690f2c5d59c1bb5

src/com/android/settings/display/BrightnessLevelPreferenceController.java

@@ -151,14 +151,22 @@ public class BrightnessLevelPreferenceController extends AbstractPreferenceContr
         return (value - min) / (max - min);
     }
 
+    @VisibleForTesting
+    IVrManager safeGetVrManager() {
+        return IVrManager.Stub.asInterface(ServiceManager.getService(
+                Context.VR_SERVICE));
+    }
+
     @VisibleForTesting
     boolean isInVrMode() {
+        IVrManager vrManager = safeGetVrManager();
+        if (vrManager != null) {
             try {
-            return IVrManager.Stub.asInterface(ServiceManager.getService(Context.VR_SERVICE))
-                    .getVrModeState();
+                return vrManager.getVrModeState();
             } catch (RemoteException e) {
                 Log.e(TAG, "Failed to check vr mode!", e);
             }
+        }
         return false;
     }
 }

tests/robotests/src/com/android/settings/display/BrightnessLevelPreferenceControllerTest.java

@@ -82,6 +82,12 @@ public class BrightnessLevelPreferenceControllerTest {
         assertThat(mController.isAvailable()).isTrue();
     }
 
+    @Test
+    public void isInVrMode_noVrManager_shouldAlwaysReturnFalse() {
+        doReturn(null).when(mController).safeGetVrManager();
+        assertThat(mController.isInVrMode()).isFalse();
+    }
+
     @Test
     public void onStart_shouldRegisterObserver() {
         BrightnessLevelPreferenceController controller =