Bug 726272 - [Page Thumbnails] don't capture error pages; r=dietrich

browser/base/content/browser-thumbnails.js

@@ -110,6 +110,11 @@ let gBrowserThumbnails = {
 
     let channel = aBrowser.docShell.currentDocumentChannel;
 
+    // Don't take screenshots of internally redirecting about: pages.
+    // This includes error pages.
+    if (channel.originalURI.schemeIs("about"))
+      return false;
+
     try {
       // If the channel is a nsIHttpChannel get its http status code.
       let httpChannel = channel.QueryInterface(Ci.nsIHttpChannel);

browser/components/thumbnails/test/Makefile.in

@@ -13,6 +13,7 @@ include $(topsrcdir)/config/rules.mk
 
 _BROWSER_FILES = \
 	browser_thumbnails_capture.js \
+	browser_thumbnails_bug726727.js \
 	head.js \
 	$(NULL)
 

browser/components/thumbnails/test/browser_thumbnails_bug726727.js

@@ -0,0 +1,19 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * These tests ensure that capturing a sites's thumbnail, saving it and
+ * retrieving it from the cache works.
+ */
+function runTests() {
+  // Create a tab that shows an error page.
+  let tab = gBrowser.addTab("http://non-existant.url/");
+  let browser = tab.linkedBrowser;
+
+  yield browser.addEventListener("DOMContentLoaded", function onLoad() {
+    browser.removeEventListener("DOMContentLoaded", onLoad, false);
+    executeSoon(next);
+  }, false);
+
+  ok(!gBrowserThumbnails._shouldCapture(browser), "we're not going to capture an error page");
+}