Fix null pointer exception when logging suggestions.

In monkey test, the suggestions list can become null. So, add check
for valid suggestions list before trying to iterate through the
suggestions.

Fixes: 64757618
Test: make RunSettingsRoboTests
Change-Id: Ib670808a4f222187b9cd53d7d939e71b5ce8dbae

src/com/android/settings/dashboard/DashboardAdapter.java

@@ -329,7 +329,11 @@ public class DashboardAdapter extends RecyclerView.Adapter<DashboardAdapter.Dash
     }
 
     private void logSuggestions() {
-        for (Tile suggestion : mDashboardData.getSuggestions()) {
+        final List<Tile> suggestions = mDashboardData.getSuggestions();
+        if (suggestions == null) {
+            return;
+        }
+        for (Tile suggestion : suggestions) {
             final String suggestionId = mSuggestionFeatureProvider.getSuggestionIdentifier(
                 mContext, suggestion);
             if (!mSuggestionsShownLogged.contains(suggestionId)) {