Add options and a browser-action popup.

go-back-with-backspace/pages/popup.css

Index: go-back-with-backspace/pages/popup.css
diff --git a/go-back-with-backspace/pages/popup.css b/go-back-with-backspace/pages/popup.css
new file mode 100644
index 0000000000000000000000000000000000000000..3dabde5543ce07ffeaa34bf25f213e85108db8d4
--- /dev/null
+++ b/go-back-with-backspace/pages/popup.css
@@ -0,0 +1,40 @@
+/**
+ * Copyright 2016 Google Inc. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+body {
+  direction: __MSG_@@bidi_dir__;
+  width: 300px;
+}
+
+#list_edit_button, #messages  {
+  margin-bottom: 10px;
+}
+
+#list_edit_button {
+  margin-top: 10px;
+}
+
+#current_url {
+  text-overflow: ellipsis;
+  white-space: nowrap;
+  overflow: hidden;
+}
+
+#status {
+  color: green;
+}
+
+#status.error {
+  color: red;
+}
+
+#report_page {
+  float: __MSG_@@bidi_start_edge__;
+}
+
+#open_options {
+  float: __MSG_@@bidi_end_edge__;
+}