Only handle click actions for left & middle buttons

chrome/browser/resources/md_downloads/crisper.js

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 function assert(condition, opt_message) {
   if (!condition) {
     var message = 'Assertion failed';
     if (opt_message) message = message + ': ' + opt_message;
     var error = new Error(message);
     var global = function() {
       return this;
@@ skipping 630 matching lines @@
   return assertInstanceof($(id), HTMLElement, 'Missing required element: ' + id);
 }
 
 function queryRequiredElement(selectors, opt_context) {
   var element = (opt_context || document).querySelector(selectors);
   return assertInstanceof(element, HTMLElement, 'Missing required element: ' + selectors);
 }
 
 [ 'click', 'auxclick' ].forEach(function(eventName) {
   document.addEventListener(eventName, function(e) {
+    if (e.button > 1) return;
     if (e.defaultPrevented) return;
     var eventPath = e.path;
     var anchor = null;
     if (eventPath) {
       for (var i = 0; i < eventPath.length; i++) {
         var element = eventPath[i];
         if (element.tagName === 'A' && element.href) {
           anchor = element;
           break;
         }
@@ skipping 65 matching lines @@
 
 function elide(original, maxLength) {
   if (original.length <= maxLength) return original;
   return original.substring(0, maxLength - 1) + '…';
 }
 
 function quoteString(str) {
   return str.replace(/([\\\.\+\*\?\[\^\]\$\(\)\{\}\=\!\<\>\|\:])/g, '\\$1');
 }
 
+function listenOnce(target, eventNames, callback) {
+  if (!Array.isArray(eventNames)) eventNames = eventNames.split(/ +/);
+  var removeAllAndCallCallback = function(event) {
+    eventNames.forEach(function(eventName) {
+      target.removeEventListener(eventName, removeAllAndCallCallback, false);
+    });
+    return callback(event);
+  };
+  eventNames.forEach(function(eventName) {
+    target.addEventListener(eventName, removeAllAndCallCallback, false);
+  });
+}
+
 // <if expr="is_ios">
 if (!('key' in KeyboardEvent.prototype)) {
   Object.defineProperty(KeyboardEvent.prototype, 'key', {
     get: function() {
       if (this.keyCode >= 48 && this.keyCode <= 57) return String.fromCharCode(this.keyCode);
       if (this.keyCode >= 65 && this.keyCode <= 90) {
         var result = String.fromCharCode(this.keyCode).toLowerCase();
         if (this.shiftKey) result = result.toUpperCase();
         return result;
       }
@@ skipping 6211 matching lines @@
   };
   return {
     Manager: Manager
   };
 });
 
 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 window.addEventListener('load', downloads.Manager.onLoad);