Don't reload after updating if a tab is in use

extensions/chromium/pdfHandler.html

@@ -22,3 +22,4 @@
 <script src="pdfHandler-v2.js"></script>
 <script src="pdfHandler-vcros.js"></script>
 <script src="pageAction/background.js"></script>
+<script src="suppress-update.js"></script>

extensions/chromium/suppress-update.js

@@ -0,0 +1,29 @@
+/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set shiftwidth=2 tabstop=2 autoindent cindent expandtab: */
+/*
+Copyright 2015 Mozilla Foundation
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+/* globals chrome */
+
+'use strict';
+
+// Do not reload the extension when an update becomes available, UNLESS the PDF
+// viewer is not displaying any PDF files. Otherwise the tabs would close, which
+// is quite disruptive (crbug.com/511670).
+chrome.runtime.onUpdateAvailable.addListener(function() {
+    if (chrome.extension.getViews({type: 'tab'}).length === 0) {
+        chrome.runtime.reload();
+    }
+});