Browser Plugin: Navigating to the same URL after crash should load a new guest

chrome/renderer/resources/extensions/web_view.js

 // Copyright (c) 2012 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.
 
 // Shim that simulates a <webview> tag via Mutation Observers.
 //
 // The actual tag is implemented via the browser plugin. The internals of this
 // are hidden via Shadow DOM.
 
 var watchForTag = require("tagWatcher").watchForTag;
@@ skipping 138 matching lines @@
  */
 WebView.prototype.handleObjectMutation_ = function(mutation) {
   // This observer monitors mutations to attributes of the BrowserPlugin and
   // updates the <webview> attributes accordingly.
   if (!this.objectNode_.hasAttribute(mutation.attributeName)) {
     // If an attribute is removed from the BrowserPlugin, then remove it
     // from the <webview> as well.
     this.node_.removeAttribute(mutation.attributeName);
   } else {
     // Update the <webview> attribute to match the BrowserPlugin attribute.
-    this.node_.setAttribute(mutation.attributeName,
-        this.objectNode_.getAttribute(mutation.attributeName));
+    // Note: Calling setAttribute on <webview> will trigger its mutation
+    // observer which will then propagate that attribute to BrowserPlugin. In
+    // cases where we permit assigning a BrowserPlugin attribute the same value
+    // again (such as navigation when crashed), this could end up in an infinite
+    // loop. Thus, we avoid this loop by only updating the <webview> attribute
+    // if the BrowserPlugin attributes differs from it.
+    var oldValue = this.node_.getAttribute(mutation.attributeName);
+    var newValue = this.objectNode_.getAttribute(mutation.attributeName);
+    if (newValue != oldValue) {
+      this.node_.setAttribute(mutation.attributeName, newValue);
+    }
   }
 };
 
 /**
  * @private
  */
 WebView.prototype.setupEvent_ = function(eventname, attribs) {
   var node = this.node_;
   this.objectNode_.addEventListener('-internal-' + eventname, function(e) {
     var evt = new Event(eventname, { bubbles: true });
     var detail = e.detail ? JSON.parse(e.detail) : {};
     attribs.forEach(function(attribName) {
       evt[attribName] = detail[attribName];
     });
     node.dispatchEvent(evt);
   });
 }