Enable pinch-zoom on the new login page.

extensions/renderer/resources/guest_view/web_view_attributes.js

 // Copyright 2014 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.
 
 // This module implements the attributes of the <webview> tag.
 
 var GuestViewInternal =
     require('binding').Binding.create('guestViewInternal').generate();
 var WebViewImpl = require('webView').WebViewImpl;
 var WebViewConstants = require('webViewConstants').WebViewConstants;
@@ skipping 74 matching lines @@
 AllowTransparencyAttribute.prototype.handleMutation = function(oldValue,
                                                                newValue) {
   if (!this.webViewImpl.guest.getId()) {
     return;
   }
 
   WebViewInternal.setAllowTransparency(this.webViewImpl.guest.getId(),
                                        this.getValue());
 };
 
+// Attribute that specifies whether transparency is allowed in the webview.
+function AllowScalingAttribute(webViewImpl) {
+  BooleanAttribute.call(
+      this, WebViewConstants.ATTRIBUTE_ALLOWSCALING, webViewImpl);
+}
+
+AllowScalingAttribute.prototype.__proto__ = BooleanAttribute.prototype;
+
+AllowScalingAttribute.prototype.handleMutation = function(oldValue,
+                                                          newValue) {
+  if (!this.webViewImpl.guest.getId()) {
+    return;
+  }
+
+  WebViewInternal.setAllowScaling(this.webViewImpl.guest.getId(),
+                                  this.getValue());
+};
+
 // Attribute used to define the demension limits of autosizing.
 function AutosizeDimensionAttribute(name, webViewImpl) {
   WebViewAttribute.call(this, name, webViewImpl);
 }
 
 AutosizeDimensionAttribute.prototype.__proto__ = WebViewAttribute.prototype;
 
 AutosizeDimensionAttribute.prototype.getValue = function() {
   return parseInt(this.webViewImpl.element.getAttribute(this.name)) || 0;
 };
@@ skipping 152 matching lines @@
 };
 
 // -----------------------------------------------------------------------------
 
 // Sets up all of the webview attributes.
 WebViewImpl.prototype.setupWebViewAttributes = function() {
   this.attributes = {};
 
   this.attributes[WebViewConstants.ATTRIBUTE_ALLOWTRANSPARENCY] =
       new AllowTransparencyAttribute(this);
+  this.attributes[WebViewConstants.ATTRIBUTE_ALLOWSCALING] =
+      new AllowScalingAttribute(this);
   this.attributes[WebViewConstants.ATTRIBUTE_AUTOSIZE] =
       new AutosizeAttribute(this);
   this.attributes[WebViewConstants.ATTRIBUTE_NAME] =
       new NameAttribute(this);
   this.attributes[WebViewConstants.ATTRIBUTE_PARTITION] =
       new PartitionAttribute(this);
   this.attributes[WebViewConstants.ATTRIBUTE_SRC] =
       new SrcAttribute(this);
 
   var autosizeAttributes = [WebViewConstants.ATTRIBUTE_MAXHEIGHT,
                             WebViewConstants.ATTRIBUTE_MAXWIDTH,
                             WebViewConstants.ATTRIBUTE_MINHEIGHT,
                             WebViewConstants.ATTRIBUTE_MINWIDTH];
   for (var i = 0; autosizeAttributes[i]; ++i) {
     this.attributes[autosizeAttributes[i]] =
         new AutosizeDimensionAttribute(autosizeAttributes[i], this);
   }
 };