Deal with the case that no print services are installed.

Bug: 27530312
Change-Id: Idd709e66d72efcca4928b471f138f8be66e7ab00

src/com/android/settings/print/PrintSettingsFragment.java

@@ -584,6 +584,8 @@ public class PrintSettingsFragment extends ProfileSettingsPreferenceFragment
             // updated until this function is called again
             List<PrintServiceInfo> services =
                     printManager.getPrintServices(PrintManager.ALL_SERVICES);
+
+            if (services != null) {
                 final int serviceCount = services.size();
                 for (int i = 0; i < serviceCount; i++) {
                     PrintServiceInfo service = services.get(i);
@@ -600,6 +602,7 @@ public class PrintSettingsFragment extends ProfileSettingsPreferenceFragment
                     data.screenTitle = screenTitle;
                     indexables.add(data);
                 }
+            }
 
             return indexables;
         }