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

extensions/renderer/resources/guest_view/guest_view.js

Index: extensions/renderer/resources/guest_view/guest_view.js
diff --git a/extensions/renderer/resources/guest_view/guest_view.js b/extensions/renderer/resources/guest_view/guest_view.js
index 8ff4f3c52b30d52bce6d408d72adbc25404e505b..9d656726f238df31cd7ea676e382b0f640c8ae16 100644
--- a/extensions/renderer/resources/guest_view/guest_view.js
+++ b/extensions/renderer/resources/guest_view/guest_view.js
@@ -133,6 +133,10 @@ GuestViewImpl.prototype.checkState = function(action) {
   return true;
 };
 
+GuestViewImpl.prototype.setContentWindow = function(contentWindow) {
+  this.contentWindow = contentWindow;
+};
+
 // Internal implementation of attach().
 GuestViewImpl.prototype.attachImpl = function(
     internalInstanceId, viewInstanceId, attachParams, callback) {
@@ -321,6 +325,11 @@ GuestView.prototype.getContentWindow = function() {
   return internal.contentWindow;
 };
 
+GuestView.prototype.setContentWindow = function(contentWindow) {
+  var internal = privates(this).internal;
+  return internal.setContentWindow(contentWindow);
+};
+
 // Returns the ID for this guestview.
 GuestView.prototype.getId = function() {
   var internal = privates(this).internal;