Add simple null checks to StorageWizard*, also listen to...

the disk destroyed event.

Bug 21336042

Change-Id: I9f53501a6122a4a9046774e3c4c08b5d6d6f8552

src/com/android/settings/deviceinfo/StorageWizardMigrateProgress.java

@@ -39,10 +39,12 @@ public class StorageWizardMigrateProgress extends StorageWizardBase {
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
+        if (mVolume == null) {
+            finish();
+            return;
+        }
         setContentView(R.layout.storage_wizard_progress);
 
-        Preconditions.checkNotNull(mVolume);
-
         mMoveId = getIntent().getIntExtra(EXTRA_MOVE_ID, -1);
 
         final String descrip = mStorage.getBestVolumeDescription(mVolume);