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

extensions/renderer/resources/guest_view/web_view/web_view.js

Index: extensions/renderer/resources/guest_view/web_view/web_view.js
diff --git a/extensions/renderer/resources/guest_view/web_view/web_view.js b/extensions/renderer/resources/guest_view/web_view/web_view.js
index fd0e45c81b01e04239d6704d51194cc3d1cfff2d..254d56b1bf06be30a88c4804b6db774a2130f496 100644
--- a/extensions/renderer/resources/guest_view/web_view/web_view.js
+++ b/extensions/renderer/resources/guest_view/web_view/web_view.js
@@ -14,11 +14,17 @@ var WebViewConstants = require('webViewConstants').WebViewConstants;
 var WebViewEvents = require('webViewEvents').WebViewEvents;
 var WebViewInternal = require('webViewInternal').WebViewInternal;
 
+var IdGenerator = requireNative('id_generator');
+var GuestViewInternalNatives = requireNative('guest_view_internal');
+
+var LOG = function(msg) { window.console.log(msg); };
+
 // Represents the internal state of <webview>.
 function WebViewImpl(webviewElement) {
   GuestViewContainer.call(this, webviewElement, 'webview');
   this.cachedZoom = 1;
   this.setupElementProperties();
+  this.isSitePerProcess = GuestViewInternalNatives.IsSitePerProcess();
   new WebViewEvents(this, this.viewInstanceId);
 }
 
@@ -92,7 +98,11 @@ WebViewImpl.prototype.setupElementProperties = function() {
   // dynamic getter value.
   Object.defineProperty(this.element, 'contentWindow', {
     get: function() {
-      return this.guest.getContentWindow();
+      if (this.isSitePerProcess) {
+        return this.getBrowserPluginElement().contentWindow;
+      } else {
+        return this.guest.getContentWindow();
+      }
     }.bind(this),
     // No setter.
     enumerable: true
@@ -189,6 +199,12 @@ WebViewImpl.prototype.attachWindow = function(opt_guestInstanceId) {
     this.guest = new GuestView('webview', opt_guestInstanceId);
   }
 
+  if (this.isSitePerProcess) {
+    var generatedID = IdGenerator.GetNextId();
+    this.onInternalInstanceID(generatedID);
+    return true;
+  }
+
   return GuestViewContainer.prototype.attachWindow.call(this);
 };