diff -r 000000000000 -r 6474c204b198 toolkit/components/thumbnails/test/browser_thumbnails_bg_destroy_browser.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/components/thumbnails/test/browser_thumbnails_bg_destroy_browser.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,29 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+function runTests() {
+  let url1 = "http://example.com/1";
+  ok(!thumbnailExists(url1), "First file should not exist yet.");
+
+  let url2 = "http://example.com/2";
+  ok(!thumbnailExists(url2), "Second file should not exist yet.");
+
+  let defaultTimeout = BackgroundPageThumbs._destroyBrowserTimeout;
+  BackgroundPageThumbs._destroyBrowserTimeout = 1000;
+
+  yield bgCapture(url1);
+  ok(thumbnailExists(url1), "First file should exist after capture.");
+  removeThumbnail(url1);
+
+  yield wait(2000);
+  is(BackgroundPageThumbs._thumbBrowser, undefined,
+     "Thumb browser should be destroyed after timeout.");
+  BackgroundPageThumbs._destroyBrowserTimeout = defaultTimeout;
+
+  yield bgCapture(url2);
+  ok(thumbnailExists(url2), "Second file should exist after capture.");
+  removeThumbnail(url2);
+
+  isnot(BackgroundPageThumbs._thumbBrowser, undefined,
+        "Thumb browser should exist immediately after capture.");
+}