diff -r 000000000000 -r 6474c204b198 mobile/android/base/sync/repositories/StoreTrackingRepositorySession.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mobile/android/base/sync/repositories/StoreTrackingRepositorySession.java	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,102 @@
+/* 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.repositories;
+
+import java.util.Collection;
+import java.util.Iterator;
+
+import org.mozilla.gecko.background.common.log.Logger;
+import org.mozilla.gecko.sync.repositories.delegates.RepositorySessionBeginDelegate;
+import org.mozilla.gecko.sync.repositories.delegates.RepositorySessionFinishDelegate;
+import org.mozilla.gecko.sync.repositories.domain.Record;
+
+public abstract class StoreTrackingRepositorySession extends RepositorySession {
+  private static final String LOG_TAG = "StoreTrackSession";
+  protected StoreTracker storeTracker;
+
+  protected static StoreTracker createStoreTracker() {
+    return new HashSetStoreTracker();
+  }
+
+  public StoreTrackingRepositorySession(Repository repository) {
+    super(repository);
+  }
+
+  @Override
+  public void begin(RepositorySessionBeginDelegate delegate) throws InvalidSessionTransitionException {
+    RepositorySessionBeginDelegate deferredDelegate = delegate.deferredBeginDelegate(delegateQueue);
+    try {
+      super.sharedBegin();
+    } catch (InvalidSessionTransitionException e) {
+      deferredDelegate.onBeginFailed(e);
+      return;
+    }
+    // Or do this in your own subclass.
+    storeTracker = createStoreTracker();
+    deferredDelegate.onBeginSucceeded(this);
+  }
+
+  @Override
+  protected synchronized void trackGUID(String guid) {
+    if (this.storeTracker == null) {
+      throw new IllegalStateException("Store tracker not yet initialized!");
+    }
+    this.storeTracker.trackRecordForExclusion(guid);
+  }
+
+  @Override
+  protected synchronized void untrackGUID(String guid) {
+    if (this.storeTracker == null) {
+      throw new IllegalStateException("Store tracker not yet initialized!");
+    }
+    this.storeTracker.untrackStoredForExclusion(guid);
+  }
+
+  @Override
+  protected synchronized void untrackGUIDs(Collection<String> guids) {
+    if (this.storeTracker == null) {
+      throw new IllegalStateException("Store tracker not yet initialized!");
+    }
+    if (guids == null) {
+      return;
+    }
+    for (String guid : guids) {
+      this.storeTracker.untrackStoredForExclusion(guid);
+    }
+  }
+
+  protected void trackRecord(Record record) {
+
+    Logger.debug(LOG_TAG, "Tracking record " + record.guid +
+                           " (" + record.lastModified + ") to avoid re-upload.");
+    // Future: we care about the timestamp…
+    trackGUID(record.guid);
+  }
+
+  protected void untrackRecord(Record record) {
+    Logger.debug(LOG_TAG, "Un-tracking record " + record.guid + ".");
+    untrackGUID(record.guid);
+  }
+
+  @Override
+  public Iterator<String> getTrackedRecordIDs() {
+    if (this.storeTracker == null) {
+      throw new IllegalStateException("Store tracker not yet initialized!");
+    }
+    return this.storeTracker.recordsTrackedForExclusion();
+  }
+
+  @Override
+  public void abort(RepositorySessionFinishDelegate delegate) {
+    this.storeTracker = null;
+    super.abort(delegate);
+  }
+
+  @Override
+  public void finish(RepositorySessionFinishDelegate delegate) throws InactiveSessionException {
+    super.finish(delegate);
+    this.storeTracker = null;
+  }
+}