Handle reset of recommended services

Change-Id: I778f8b7a081d433ca0f21361c2ca8dcd48303935
Fixes: 30389837
diff --git a/packages/PrintSpooler/src/com/android/printspooler/ui/AddPrinterActivity.java b/packages/PrintSpooler/src/com/android/printspooler/ui/AddPrinterActivity.java
index 2f58de5..c06e849 100644
--- a/packages/PrintSpooler/src/com/android/printspooler/ui/AddPrinterActivity.java
+++ b/packages/PrintSpooler/src/com/android/printspooler/ui/AddPrinterActivity.java
@@ -737,9 +737,11 @@
         public void updateInstalledServices(List<PrintServiceInfo> services) {
             mInstalledServices.clear();
 
-            final int numServices = services.size();
-            for (int i = 0; i < numServices; i++) {
-                mInstalledServices.add(services.get(i).getComponentName().getPackageName());
+            if (services != null) {
+                final int numServices = services.size();
+                for (int i = 0; i < numServices; i++) {
+                    mInstalledServices.add(services.get(i).getComponentName().getPackageName());
+                }
             }
 
             filterRecommendations();