diff -r 000000000000 -r 6474c204b198 mobile/android/base/sync/HTTPFailureException.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mobile/android/base/sync/HTTPFailureException.java	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,47 @@
+/* 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;
+
+import org.mozilla.gecko.sync.net.SyncStorageResponse;
+
+import android.content.SyncResult;
+
+public class HTTPFailureException extends SyncException {
+  private static final long serialVersionUID = -5415864029780770619L;
+  public SyncStorageResponse response;
+
+  public HTTPFailureException(SyncStorageResponse response) {
+    this.response = response;
+  }
+
+  @Override
+  public String toString() {
+    String errorMessage;
+    try {
+      errorMessage = this.response.getErrorMessage();
+    } catch (Exception e) {
+      // Oh well.
+      errorMessage = "[unknown error message]";
+    }
+    return "<HTTPFailureException " + this.response.getStatusCode() +
+           " :: (" + errorMessage + ")>";
+  }
+
+  @Override
+  public void updateStats(GlobalSession globalSession, SyncResult syncResult) {
+    switch (response.getStatusCode()) {
+    case 401:
+      // Node reassignment 401s get handled internally.
+      syncResult.stats.numAuthExceptions++;
+      return;
+    case 500:
+    case 501:
+    case 503:
+      // TODO: backoff.
+      syncResult.stats.numIoExceptions++;
+      return;
+    }
+  }
+}