diff -r 000000000000 -r 6474c204b198 toolkit/components/telemetry/TelemetryLog.jsm
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/components/telemetry/TelemetryLog.jsm	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,35 @@
+/* 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/. */
+
+this.EXPORTED_SYMBOLS = ["TelemetryLog"];
+
+const Cc = Components.classes;
+const Ci = Components.interfaces;
+
+const Telemetry = Cc["@mozilla.org/base/telemetry;1"].getService(Ci.nsITelemetry);
+var gLogEntries = [];
+
+this.TelemetryLog = Object.freeze({
+  log: function(id, data) {
+    id = String(id);
+    var ts;
+    try {
+      ts = Math.floor(Telemetry.msSinceProcessStart());
+    } catch(e) {
+      // If timestamp is screwed up, we just give up instead of making up
+      // data.
+      return;
+    }
+
+    var entry = [id, ts];
+    if (data !== undefined) {
+      entry = entry.concat(Array.prototype.map.call(data, String));
+    }
+    gLogEntries.push(entry);
+  },
+
+  entries: function() {
+    return gLogEntries;
+  }
+});