DO NOT MERGE: Always return non null from getGpsStatus

Even though getGpsStatus is marked Nullable, some applications expect it
to always return non-null.

Bug: 161311411
Test: presubmits
Change-Id: I8d58621588253af1dc917711e230cfd176afec37

location/java/android/location/GpsStatus.java

@@ -151,6 +151,15 @@ public final class GpsStatus {
         return status;
     }
 
+    /**
+     * Builds an empty GpsStatus.
+     *
+     * @hide
+     */
+    static GpsStatus createEmpty() {
+        return new GpsStatus();
+    }
+
     private GpsStatus() {
     }
 

location/java/android/location/LocationManager.java

@@ -1922,12 +1922,17 @@ public class LocationManager {
 
         GnssStatus gnssStatus = mGnssStatusListenerManager.getGnssStatus();
         int ttff = mGnssStatusListenerManager.getTtff();
+
+        // even though this method is marked nullable, there are legacy applications that expect
+        // this to never return null, so avoid breaking those apps
         if (gnssStatus != null) {
             if (status == null) {
                 status = GpsStatus.create(gnssStatus, ttff);
             } else {
                 status.setStatus(gnssStatus, ttff);
             }
+        } else if (status == null) {
+            status = GpsStatus.createEmpty();
         }
         return status;
     }