diff -r 000000000000 -r 6474c204b198 mobile/android/base/fxa/activities/FxAccountSetupTask.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mobile/android/base/fxa/activities/FxAccountSetupTask.java	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,172 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.gecko.fxa.activities;
+
+import java.io.UnsupportedEncodingException;
+import java.util.concurrent.CountDownLatch;
+
+import org.mozilla.gecko.background.common.log.Logger;
+import org.mozilla.gecko.background.fxa.FxAccountClient;
+import org.mozilla.gecko.background.fxa.FxAccountClient10.RequestDelegate;
+import org.mozilla.gecko.background.fxa.FxAccountClient20.LoginResponse;
+import org.mozilla.gecko.background.fxa.FxAccountClientException.FxAccountClientRemoteException;
+import org.mozilla.gecko.background.fxa.PasswordStretcher;
+import org.mozilla.gecko.fxa.activities.FxAccountSetupTask.InnerRequestDelegate;
+
+import android.content.Context;
+import android.os.AsyncTask;
+
+/**
+ * An <code>AsyncTask</code> wrapper around signing up for, and signing in to, a
+ * Firefox Account.
+ * <p>
+ * It's strange to add explicit blocking to callback-threading code, but we do
+ * it here to take advantage of Android's built in support for background work.
+ * We really want to avoid making a threading mistake that brings down the whole
+ * process.
+ */
+abstract class FxAccountSetupTask<T> extends AsyncTask<Void, Void, InnerRequestDelegate<T>> {
+  private static final String LOG_TAG = FxAccountSetupTask.class.getSimpleName();
+
+  public interface ProgressDisplay {
+    public void showProgress();
+    public void dismissProgress();
+  }
+
+  protected final Context context;
+  protected final FxAccountClient client;
+  protected final ProgressDisplay progressDisplay;
+
+  // Initialized lazily.
+  protected byte[] quickStretchedPW;
+
+  // AsyncTask's are one-time-use, so final members are fine.
+  protected final CountDownLatch latch = new CountDownLatch(1);
+  protected final InnerRequestDelegate<T> innerDelegate = new InnerRequestDelegate<T>(latch);
+
+  protected final RequestDelegate<T> delegate;
+
+  public FxAccountSetupTask(Context context, ProgressDisplay progressDisplay, FxAccountClient client, RequestDelegate<T> delegate) {
+    this.context = context;
+    this.client = client;
+    this.delegate = delegate;
+    this.progressDisplay = progressDisplay;
+  }
+
+  @Override
+  protected void onPreExecute() {
+    if (progressDisplay != null) {
+      progressDisplay.showProgress();
+    }
+  }
+
+  @Override
+  protected void onPostExecute(InnerRequestDelegate<T> result) {
+    if (progressDisplay != null) {
+      progressDisplay.dismissProgress();
+    }
+
+    // We are on the UI thread, and need to invoke these callbacks here to allow UI updating.
+    if (innerDelegate.failure != null) {
+      delegate.handleFailure(innerDelegate.failure);
+    } else if (innerDelegate.exception != null) {
+      delegate.handleError(innerDelegate.exception);
+    } else {
+      delegate.handleSuccess(result.response);
+    }
+  }
+
+  @Override
+  protected void onCancelled(InnerRequestDelegate<T> result) {
+    if (progressDisplay != null) {
+      progressDisplay.dismissProgress();
+    }
+    delegate.handleError(new IllegalStateException("Task was cancelled."));
+  }
+
+  protected static class InnerRequestDelegate<T> implements RequestDelegate<T> {
+    protected final CountDownLatch latch;
+    public T response = null;
+    public Exception exception = null;
+    public FxAccountClientRemoteException failure = null;
+
+    protected InnerRequestDelegate(CountDownLatch latch) {
+      this.latch = latch;
+    }
+
+    @Override
+    public void handleError(Exception e) {
+      Logger.error(LOG_TAG, "Got exception.");
+      this.exception = e;
+      latch.countDown();
+    }
+
+    @Override
+    public void handleFailure(FxAccountClientRemoteException e) {
+      Logger.warn(LOG_TAG, "Got failure.");
+      this.failure = e;
+      latch.countDown();
+    }
+
+    @Override
+    public void handleSuccess(T result) {
+      Logger.info(LOG_TAG, "Got success.");
+      this.response = result;
+      latch.countDown();
+    }
+  }
+
+  public static class FxAccountCreateAccountTask extends FxAccountSetupTask<LoginResponse> {
+    private static final String LOG_TAG = FxAccountCreateAccountTask.class.getSimpleName();
+
+    protected final byte[] emailUTF8;
+    protected final PasswordStretcher passwordStretcher;
+
+    public FxAccountCreateAccountTask(Context context, ProgressDisplay progressDisplay, String email, PasswordStretcher passwordStretcher, FxAccountClient client, RequestDelegate<LoginResponse> delegate) throws UnsupportedEncodingException {
+      super(context, progressDisplay, client, delegate);
+      this.emailUTF8 = email.getBytes("UTF-8");
+      this.passwordStretcher = passwordStretcher;
+    }
+
+    @Override
+    protected InnerRequestDelegate<LoginResponse> doInBackground(Void... arg0) {
+      try {
+        client.createAccountAndGetKeys(emailUTF8, passwordStretcher, innerDelegate);
+        latch.await();
+        return innerDelegate;
+      } catch (Exception e) {
+        Logger.error(LOG_TAG, "Got exception logging in.", e);
+        delegate.handleError(e);
+      }
+      return null;
+    }
+  }
+
+  public static class FxAccountSignInTask extends FxAccountSetupTask<LoginResponse> {
+    protected static final String LOG_TAG = FxAccountSignInTask.class.getSimpleName();
+
+    protected final byte[] emailUTF8;
+    protected final PasswordStretcher passwordStretcher;
+
+    public FxAccountSignInTask(Context context, ProgressDisplay progressDisplay, String email, PasswordStretcher passwordStretcher, FxAccountClient client, RequestDelegate<LoginResponse> delegate) throws UnsupportedEncodingException {
+      super(context, progressDisplay, client, delegate);
+      this.emailUTF8 = email.getBytes("UTF-8");
+      this.passwordStretcher = passwordStretcher;
+    }
+
+    @Override
+    protected InnerRequestDelegate<LoginResponse> doInBackground(Void... arg0) {
+      try {
+        client.loginAndGetKeys(emailUTF8, passwordStretcher, innerDelegate);
+        latch.await();
+        return innerDelegate;
+      } catch (Exception e) {
+        Logger.error(LOG_TAG, "Got exception signing in.", e);
+        delegate.handleError(e);
+      }
+      return null;
+    }
+  }
+}