Context isn't good enough, actually check for null

Bug: 25606212
Change-Id: Ic765d5a37fa19ecd22bb47694514e6ee0bdb84a5
diff --git a/src/com/android/settings/DataUsageSummary.java b/src/com/android/settings/DataUsageSummary.java
index 7c6f502..bcd05bd 100644
--- a/src/com/android/settings/DataUsageSummary.java
+++ b/src/com/android/settings/DataUsageSummary.java
@@ -552,6 +552,7 @@
     @Override
     public void onPrepareOptionsMenu(Menu menu) {
         final Context context = getContext();
+        if (context == null) return;
         final boolean appDetailMode = isAppDetailMode();
         final boolean isAdmin = mUserManager.isAdminUser();