diff -r 000000000000 -r 6474c204b198 mobile/android/base/sync/synchronizer/Synchronizer.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mobile/android/base/sync/synchronizer/Synchronizer.java	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,105 @@
+/* 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.sync.synchronizer;
+
+import org.mozilla.gecko.background.common.log.Logger;
+import org.mozilla.gecko.sync.SynchronizerConfiguration;
+import org.mozilla.gecko.sync.repositories.Repository;
+import org.mozilla.gecko.sync.repositories.RepositorySessionBundle;
+
+import android.content.Context;
+
+/**
+ * I perform a sync.
+ *
+ * Initialize me by calling `load` with a SynchronizerConfiguration.
+ *
+ * Start synchronizing by calling `synchronize` with a SynchronizerDelegate. I
+ * provide coarse-grained feedback by calling my delegate's callback methods.
+ *
+ * I always call exactly one of my delegate's `onSynchronized` or
+ * `onSynchronizeFailed` callback methods. In addition, I call
+ * `onSynchronizeAborted` before `onSynchronizeFailed` when I encounter a fetch,
+ * store, or session error while synchronizing.
+ *
+ * After synchronizing, call `save` to get back a SynchronizerConfiguration with
+ * updated bundle information.
+ */
+public class Synchronizer implements SynchronizerSessionDelegate {
+  public static final String LOG_TAG = "SyncDelSDelegate";
+
+  protected String configSyncID; // Used to pass syncID from load() back into save().
+
+  protected SynchronizerDelegate synchronizerDelegate;
+
+  protected SynchronizerSession session = null;
+
+  public SynchronizerSession getSynchronizerSession() {
+    return session;
+  }
+
+  @Override
+  public void onInitialized(SynchronizerSession session) {
+    session.synchronize();
+  }
+
+  @Override
+  public void onSynchronized(SynchronizerSession synchronizerSession) {
+    Logger.debug(LOG_TAG, "Got onSynchronized.");
+    Logger.debug(LOG_TAG, "Notifying SynchronizerDelegate.");
+    this.synchronizerDelegate.onSynchronized(synchronizerSession.getSynchronizer());
+  }
+
+  @Override
+  public void onSynchronizeSkipped(SynchronizerSession synchronizerSession) {
+    Logger.debug(LOG_TAG, "Got onSynchronizeSkipped.");
+    Logger.debug(LOG_TAG, "Notifying SynchronizerDelegate as if on success.");
+    this.synchronizerDelegate.onSynchronized(synchronizerSession.getSynchronizer());
+  }
+
+  @Override
+  public void onSynchronizeFailed(SynchronizerSession session,
+      Exception lastException, String reason) {
+    this.synchronizerDelegate.onSynchronizeFailed(session.getSynchronizer(), lastException, reason);
+  }
+
+  public Repository repositoryA;
+  public Repository repositoryB;
+  public RepositorySessionBundle bundleA;
+  public RepositorySessionBundle bundleB;
+
+  /**
+   * Fetch a synchronizer session appropriate for this <code>Synchronizer</code>
+   */
+  protected SynchronizerSession newSynchronizerSession() {
+    return new SynchronizerSession(this, this);
+  }
+
+  /**
+   * Start synchronizing, calling delegate's callback methods.
+   */
+  public void synchronize(Context context, SynchronizerDelegate delegate) {
+    this.synchronizerDelegate = delegate;
+    this.session = newSynchronizerSession();
+    this.session.init(context, bundleA, bundleB);
+  }
+
+  public SynchronizerConfiguration save() {
+    return new SynchronizerConfiguration(configSyncID, bundleA, bundleB);
+  }
+
+  /**
+   * Set my repository session bundles from a SynchronizerConfiguration.
+   *
+   * This method is not thread-safe.
+   *
+   * @param config
+   */
+  public void load(SynchronizerConfiguration config) {
+    bundleA = config.remoteBundle;
+    bundleB = config.localBundle;
+    configSyncID  = config.syncID;
+  }
+}