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

the disk destroyed event.

Bug 21336042

Change-Id: I9f53501a6122a4a9046774e3c4c08b5d6d6f8552

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

@@ -36,6 +36,11 @@ public class StorageWizardMigrateConfirm extends StorageWizardBase {
             mVolume = findFirstVolume(VolumeInfo.TYPE_PRIVATE);
         }
 
+        if (mVolume == null) {
+            finish();
+            return;
+        }
+
         final VolumeInfo sourceVol = getPackageManager().getPrimaryStorageCurrentVolume();
         final String sourceDescrip = mStorage.getBestVolumeDescription(sourceVol);
         final String targetDescrip = mStorage.getBestVolumeDescription(mVolume);