Update platform_app.js to work even if window.history is not replaceable

chrome/renderer/resources/extensions/platform_app.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.
 
 var $console = window.console;
 
 /**
  * Returns a function that logs a 'not available' error to the console and
  * returns undefined.
  *
@@ skipping 57 matching lines @@
 function disableMethods(object, objectName, methodNames, useThrowingStubs) {
   $Array.forEach(methodNames, function(methodName) {
     var messagePrefix = objectName + '.' + methodName + '()';
     object[methodName] = useThrowingStubs ?
         generateThrowingMethodStub(messagePrefix) :
         generateDisabledMethodStub(messagePrefix);
   });
 }
 
 /**
+ * Deletes the given methods from the passed in objext.
+ *
+ * This may be needed for feature detection as ('methodName' in object) will
+ * return false after this.
+ *
+ * @param {Object} object The object with methods to disable. The prototype is
+ *     preferred.
+ * @param {Array.<string>} methodNames names of methods to delete.
+ */
+function deleteMethods(object, methodNames) {
+  $Array.forEach(methodNames, function(methodName) {
+    delete object[methodName];
+  });
+}
+
+/**
  * Replaces the given properties of the passed in object with stubs that log
  * 'not available' warnings to the console and return undefined when gotten. If
  * a property's setter is later invoked, the getter and setter are restored to
  * default behaviors.
  *
  * @param {Object} object The object with properties to disable. The prototype
  *     is preferred.
  * @param {string} objectName The display name to use in the error message
  *     thrown by the getter stub (this is the name that the object is commonly
  *     referred to by web developers, e.g. "document" instead of
@@ skipping 50 matching lines @@
       configurable: true,
       enumerable: false,
       get: function() {
         return;
       },
       set: stub
     });
   });
 }
 
+/**
+ * Deletes the given properties of the passed in object.
+ *
+ * This may be needed for feature detection as ('propertyName' in object) will
+ * return false after this.
+ *
+ * @param {Object} object The object with properties to disable.
+ * @param {Array.<string>} propertyNames names of properties to delete.
+ */
+function deleteProperties(object, propertyNames) {
+  $Array.forEach(propertyNames, function(propertyName) {
+    delete object[propertyName];
+  });
+}
+
 // Disable benign Document methods.
 disableMethods(HTMLDocument.prototype, 'document', ['open', 'clear', 'close']);
 
 // Replace evil Document methods with exception-throwing stubs.
 disableMethods(HTMLDocument.prototype, 'document', ['write', 'writeln'], true);
 
-// Disable history.
-window.history = {};

[arv (Not doing code reviews), 2014/04/22 13:54:42]

This one could have been replaced with a defineProperty instead.

[Inactive, 2014/04/22 14:43:54]

Would be much simpler, let me give this a try.

[Inactive, 2014/04/22 14:59:59]

Done, thanks. Much simpler indeed.

+// Disable history API.
 disableGetters(window.history, 'history', ['back', 'forward', 'go', 'length']);
+// These are part of the HTML5 History API that are feature detected, so we
+// remove them altogether, allowing apps to have fallback behavior.
+deleteProperties(window.history, ['state']);
+deleteMethods(History.prototype, ['pushState', 'replaceState']);
 
 // Disable find.
 disableMethods(Window.prototype, 'window', ['find']);
 
 // Disable modal dialogs. Shell windows disable these anyway, but it's nice to
 // warn.
 disableMethods(Window.prototype, 'window', ['alert', 'confirm', 'prompt']);
 
 // Disable window.*bar.
 disableGetters(window, 'window',
@@ skipping 31 matching lines @@
 
 // Disable onunload, onbeforeunload.
 disableSetters(Window.prototype, 'window', ['onbeforeunload', 'onunload']);
 var windowAddEventListener = Window.prototype.addEventListener;
 Window.prototype.addEventListener = function(type) {
   if (type === 'unload' || type === 'beforeunload')
     generateDisabledMethodStub(type)();
   else
     return $Function.apply(windowAddEventListener, window, arguments);
 };