Make <webview> use out-of-process iframe architecture.

extensions/renderer/resources/guest_view/guest_view_container.js

Index: extensions/renderer/resources/guest_view/guest_view_container.js
diff --git a/extensions/renderer/resources/guest_view/guest_view_container.js b/extensions/renderer/resources/guest_view/guest_view_container.js
index 5b6a736758ffe04dbec929baf704ec9289618e24..952bb6a37f7fb331bb0ba326562fed33a1a0d777 100644
--- a/extensions/renderer/resources/guest_view/guest_view_container.js
+++ b/extensions/renderer/resources/guest_view/guest_view_container.js
@@ -91,6 +91,10 @@ GuestViewContainer.prototype.createBrowserPluginElement = function() {
   return browserPluginElement;
 };
 
+GuestViewContainer.prototype.getBrowserPluginElement = function() {
+  return privates(this).browserPluginElement;
+};
+
 GuestViewContainer.prototype.setupFocusPropagation = function() {
   if (!this.element.hasAttribute('tabIndex')) {
     // GuestViewContainer needs a tabIndex in order to be focusable.
@@ -184,11 +188,12 @@ GuestViewContainer.prototype.setupAttributes = function() {};
 // Registers the browser plugin <object> custom element. |viewType| is the
 // name of the specific guestview container (e.g. 'webview').
 function registerBrowserPluginElement(viewType) {
-  var proto = Object.create(HTMLObjectElement.prototype);
+  //var proto = Object.create(HTMLObjectElement.prototype);
+  var proto = Object.create(HTMLIFrameElement.prototype);
 
   proto.createdCallback = function() {
-    this.setAttribute('type', 'application/browser-plugin');
-    this.setAttribute('id', 'browser-plugin-' + IdGenerator.GetNextId());
+    //this.setAttribute('type', 'application/browser-plugin');
+    //this.setAttribute('id', 'browser-plugin-' + IdGenerator.GetNextId());
     this.style.width = '100%';
     this.style.height = '100%';
   };
@@ -198,6 +203,7 @@ function registerBrowserPluginElement(viewType) {
     var unused = this.nonExistentAttribute;
   };
 
+  /*
   proto.attributeChangedCallback = function(name, oldValue, newValue) {
     var internal = privates(this).internal;
     if (!internal) {
@@ -205,10 +211,12 @@ function registerBrowserPluginElement(viewType) {
     }
     internal.handleBrowserPluginAttributeMutation(name, oldValue, newValue);
   };
+  */
 
   GuestViewContainer[viewType + 'BrowserPlugin'] =
       DocumentNatives.RegisterElement(viewType + 'browserplugin',
-                                      {extends: 'object', prototype: proto});
+                                      //{extends: 'object', prototype: proto});
+                                      {extends: 'iframe', prototype: proto});
 
   delete proto.createdCallback;
   delete proto.attachedCallback;