Make password-setting AsyncTask survive configuration changes (screen rotation)

Robust code derived from:
http://stackoverflow.com/a/12303649

src/i2p/bote/util/TaskFragment.java

@@ -0,0 +1,69 @@
+package i2p.bote.util;
+
+import android.os.Bundle;
+import android.support.v4.app.DialogFragment;
+
+public class TaskFragment<Params, Progress, Result> extends DialogFragment {
+    RobustAsyncTask<Params, Progress, Result> mTask;
+
+    public void setTask(RobustAsyncTask<Params, Progress, Result> task) {
+        mTask = task;
+        mTask.setFragment(this);
+    }
+
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        // Retain this instance so it isn't destroyed
+        setRetainInstance(true);
+
+        // Start the task
+        if (mTask != null)
+            mTask.execute(getParams());
+    }
+
+    // This is to work around what is apparently a bug. If you don't have it
+    // here the dialog will be dismissed on rotation, so tell it not to dismiss.
+    @Override
+    public void onDestroyView() {
+        if (getDialog() != null && getRetainInstance())
+            getDialog().setDismissMessage(null);
+        super.onDestroyView();
+    }
+
+    @Override
+    public void onResume()
+    {
+        super.onResume();
+        // This is a little hacky, but we will see if the task has finished
+        // while we weren't in this activity, and then we can dismiss ourselves.
+        if (mTask == null)
+            dismiss();
+    }
+
+    public Params[] getParams() {
+        return null;
+    }
+
+    public void updateProgress(Progress... values) {}
+
+    public void taskFinished(Result result) {
+        finishTask();
+    }
+
+    public void taskCancelled(Result result) {
+        finishTask();
+    }
+
+    private void finishTask() {
+        // Make sure we check if it is resumed because we will crash if trying
+        // to dismiss the dialog after the user has switched to another app.
+        if (isResumed())
+            dismiss();
+
+        // If we aren't resumed, setting the task to null will allow us to
+        // dismiss ourselves in onResume().
+        mTask = null;
+    }
+}