Extract the element implementation logic to function mods in <webview>.

  function mods end with "$".

"element" inside <webview> is currently the plugin <object> element, i.e.
  the browser plugin. This CL makes it possible to provide a different
  implementation for the element. This CL also provides a stub
  using <iframe>. This will be used by the <webview> using OOPIF
  architecture CL: https://chromiumcodereview.appspot.com/972313002/

BUG=330264
Test=None, no visible changes.

Review URL: https://codereview.chromium.org/1165773004

Cr-Commit-Position: refs/heads/master@{#333592}

extensions/extensions.gypi

@@ -953,6 +953,7 @@
       'renderer/resources/guest_view/surface_view/surface_view.js',
       'renderer/resources/guest_view/web_view/web_view.js',
       'renderer/resources/guest_view/web_view/web_view_events.js',
+      'renderer/resources/guest_view/web_view/web_view_iframe.js',
       'renderer/resources/web_request_custom_bindings.js',
       'renderer/resources/web_request_internal_custom_bindings.js',
       'renderer/runtime_custom_bindings.cc',

extensions/renderer/dispatcher.cc

@@ -472,6 +472,15 @@ std::vector<std::pair<std::string, int> > Dispatcher::GetJsResources() {
   resources.push_back(std::make_pair("guestViewDeny", IDR_GUEST_VIEW_DENY_JS));
   resources.push_back(std::make_pair("guestViewEvents",
                                      IDR_GUEST_VIEW_EVENTS_JS));
+
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          ::switches::kSitePerProcess)) {
+    resources.push_back(std::make_pair("guestViewIframe",
+                                       IDR_GUEST_VIEW_IFRAME_JS));
+    resources.push_back(std::make_pair("guestViewIframeContainer",
+                                       IDR_GUEST_VIEW_IFRAME_CONTAINER_JS));
+  }
+
   resources.push_back(std::make_pair("imageUtil", IDR_IMAGE_UTIL_JS));
   resources.push_back(std::make_pair("json_schema", IDR_JSON_SCHEMA_JS));
   resources.push_back(std::make_pair("lastError", IDR_LAST_ERROR_JS));
@@ -509,6 +518,11 @@ std::vector<std::pair<std::string, int> > Dispatcher::GetJsResources() {
   resources.push_back(std::make_pair("webViewEvents", IDR_WEB_VIEW_EVENTS_JS));
   resources.push_back(std::make_pair("webViewInternal",
                                      IDR_WEB_VIEW_INTERNAL_CUSTOM_BINDINGS_JS));
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          ::switches::kSitePerProcess)) {
+    resources.push_back(std::make_pair("webViewIframe",
+                                       IDR_WEB_VIEW_IFRAME_JS));
+  }
   resources.push_back(
       std::make_pair(mojo::kBindingsModuleName, IDR_MOJO_BINDINGS_JS));
   resources.push_back(
@@ -1417,6 +1431,11 @@ void Dispatcher::RequireGuestViewModules(ScriptContext* context) {
     module_system->Require("webView");
     module_system->Require("webViewApiMethods");
     module_system->Require("webViewAttributes");
+
+    if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+            ::switches::kSitePerProcess)) {
+      module_system->Require("webViewIframe");
+    }
   }
 
   // The "guestViewDeny" module must always be loaded last. It registers

extensions/renderer/resources/extensions_renderer_resources.grd

@@ -28,11 +28,13 @@
       <include name="IDR_EXTENSION_VIEW_CONSTANTS_JS" file="guest_view/extension_view/extension_view_constants.js" type="BINDATA" />
       <include name="IDR_EXTENSION_VIEW_EVENTS_JS" file="guest_view/extension_view/extension_view_events.js" type="BINDATA" />
       <include name="IDR_EXTENSION_VIEW_INTERNAL_CUSTOM_BINDINGS_JS" file="guest_view/extension_view/extension_view_internal.js" type="BINDATA" />
-      <include name="IDR_GUEST_VIEW_JS" file="guest_view/guest_view.js" type="BINDATA" />
       <include name="IDR_GUEST_VIEW_ATTRIBUTES_JS" file="guest_view/guest_view_attributes.js" type="BINDATA" />
       <include name="IDR_GUEST_VIEW_CONTAINER_JS" file="guest_view/guest_view_container.js" type="BINDATA" />
       <include name="IDR_GUEST_VIEW_DENY_JS" file="guest_view/guest_view_deny.js" type="BINDATA" />
       <include name="IDR_GUEST_VIEW_EVENTS_JS" file="guest_view/guest_view_events.js" type="BINDATA" />
+      <include name="IDR_GUEST_VIEW_IFRAME_CONTAINER_JS" file="guest_view/guest_view_iframe_container.js" type="BINDATA" />
+      <include name="IDR_GUEST_VIEW_IFRAME_JS" file="guest_view/guest_view_iframe.js" type="BINDATA" />
+      <include name="IDR_GUEST_VIEW_JS" file="guest_view/guest_view.js" type="BINDATA" />
       <include name="IDR_IMAGE_UTIL_JS" file="image_util.js" type="BINDATA" />
       <include name="IDR_JSON_SCHEMA_JS" file="json_schema.js" type="BINDATA" />
       <include name="IDR_KEEP_ALIVE_JS" file="keep_alive.js" type="BINDATA" />
@@ -61,6 +63,7 @@
       <include name="IDR_WEB_VIEW_ATTRIBUTES_JS" file="guest_view/web_view/web_view_attributes.js" type="BINDATA" />
       <include name="IDR_WEB_VIEW_CONSTANTS_JS" file="guest_view/web_view/web_view_constants.js" type="BINDATA" />
       <include name="IDR_WEB_VIEW_EVENTS_JS" file="guest_view/web_view/web_view_events.js" type="BINDATA" />
+      <include name="IDR_WEB_VIEW_IFRAME_JS" file="guest_view/web_view/web_view_iframe.js" type="BINDATA" />
       <include name="IDR_WEB_VIEW_INTERNAL_CUSTOM_BINDINGS_JS" file="guest_view/web_view/web_view_internal.js" type="BINDATA" />
       <include name="IDR_WEB_VIEW_JS" file="guest_view/web_view/web_view.js" type="BINDATA" />
 

extensions/renderer/resources/guest_view/app_view/app_view.js

@@ -70,7 +70,7 @@ AppViewImpl.prototype.connect = function(app, data, callback) {
       }
       return;
     }
-    this.attachWindow();
+    this.attachWindow$();
     if (callback) {
       callback(true);
     }

extensions/renderer/resources/guest_view/extension_options/extension_options.js

@@ -41,7 +41,7 @@ ExtensionOptionsImpl.prototype.createGuest = function() {
       var createFailedEvent = new Event('createfailed', { bubbles: true });
       this.dispatchEvent(createFailedEvent);
     } else {
-      this.attachWindow();
+      this.attachWindow$();
     }
   }.bind(this));
 };

extensions/renderer/resources/guest_view/extension_view/extension_view.js

@@ -29,7 +29,7 @@ ExtensionViewImpl.setupElement = function(proto) {
 
 ExtensionViewImpl.prototype.createGuest = function() {
   this.guest.create(this.buildParams(), function() {
-    this.attachWindow();
+    this.attachWindow$();
   }.bind(this));
 };
 

extensions/renderer/resources/guest_view/guest_view.js

@@ -14,11 +14,6 @@ var GuestViewInternalNatives = requireNative('guest_view_internal');
 // Events.
 var ResizeEvent = CreateEvent('guestViewInternal.onResize');
 
-// Possible states.
-var GUEST_STATE_ATTACHED = 2;
-var GUEST_STATE_CREATED = 1;
-var GUEST_STATE_START = 0;
-
 // Error messages.
 var ERROR_MSG_ALREADY_ATTACHED = 'The guest has already been attached.';
 var ERROR_MSG_ALREADY_CREATED = 'The guest has already been created.';
@@ -35,10 +30,10 @@ var PROPERTY_ON_RESIZE = 'onresize';
 function GuestViewImpl(guestView, viewType, guestInstanceId) {
   if (guestInstanceId) {
     this.id = guestInstanceId;
-    this.state = GUEST_STATE_CREATED;
+    this.state = GuestViewImpl.GuestState.GUEST_STATE_CREATED;
   } else {
     this.id = 0;
-    this.state = GUEST_STATE_START;
+    this.state = GuestViewImpl.GuestState.GUEST_STATE_START;
   }
   this.actionQueue = [];
   this.contentWindow = null;
@@ -50,6 +45,13 @@ function GuestViewImpl(guestView, viewType, guestInstanceId) {
   this.setupOnResize();
 }
 
+// Possible states.
+GuestViewImpl.GuestState = {
+  GUEST_STATE_START: 0,
+  GUEST_STATE_CREATED: 1,
+  GUEST_STATE_ATTACHED: 2
+};
+
 // Sets up the onResize property on the GuestView.
 GuestViewImpl.prototype.setupOnResize = function() {
   $Object.defineProperty(this.guestView, PROPERTY_ON_RESIZE, {
@@ -145,7 +147,7 @@ GuestViewImpl.prototype.weakWrapper = function(func, viewInstanceId) {
 };
 
 // Internal implementation of attach().
-GuestViewImpl.prototype.attachImpl = function(
+GuestViewImpl.prototype.attachImpl$ = function(
     internalInstanceId, viewInstanceId, attachParams, callback) {
   // Check the current state.
   if (!this.checkState('attach')) {
@@ -159,7 +161,7 @@ GuestViewImpl.prototype.attachImpl = function(
   var callbackWrapper = function(callback, contentWindow) {
     // Check if attaching failed.
     if (!contentWindow) {
-      this.state = GUEST_STATE_CREATED;
+      this.state = GuestViewImpl.GuestState.GUEST_STATE_CREATED;
       this.internalInstanceId = 0;
     } else {
       // Only update the contentWindow if attaching is successful.
@@ -176,23 +178,23 @@ GuestViewImpl.prototype.attachImpl = function(
                                        callbackWrapper.bind(this, callback));
 
   this.internalInstanceId = internalInstanceId;
-  this.state = GUEST_STATE_ATTACHED;
+  this.state = GuestViewImpl.GuestState.GUEST_STATE_ATTACHED;
 
   // Detach automatically when the container is destroyed.
   GuestViewInternalNatives.RegisterDestructionCallback(
       internalInstanceId, this.weakWrapper(function() {
-    if (this.state != GUEST_STATE_ATTACHED ||
+    if (this.state != GuestViewImpl.GuestState.GUEST_STATE_ATTACHED ||
         this.internalInstanceId != internalInstanceId) {
       return;
     }
 
     this.internalInstanceId = 0;
-    this.state = GUEST_STATE_CREATED;
+    this.state = GuestViewImpl.GuestState.GUEST_STATE_CREATED;
   }, viewInstanceId));
 };
 
 // Internal implementation of create().
-GuestViewImpl.prototype.createImpl = function(createParams, callback) {
+GuestViewImpl.prototype.createImpl$ = function(createParams, callback) {
   // Check the current state.
   if (!this.checkState('create')) {
     this.handleCallback(callback);
@@ -209,7 +211,7 @@ GuestViewImpl.prototype.createImpl = function(createParams, callback) {
 
     // Check if creation failed.
     if (this.id === 0) {
-      this.state = GUEST_STATE_START;
+      this.state = GuestViewImpl.GuestState.GUEST_STATE_START;
       this.contentWindow = null;
     }
 
@@ -217,11 +219,14 @@ GuestViewImpl.prototype.createImpl = function(createParams, callback) {
     this.handleCallback(callback);
   };
 
-  GuestViewInternal.createGuest(this.viewType,
-                                createParams,
-                                callbackWrapper.bind(this, callback));
+  this.sendCreateRequest(createParams, callbackWrapper.bind(this, callback));
+
+  this.state = GuestViewImpl.GuestState.GUEST_STATE_CREATED;
+};
 
-  this.state = GUEST_STATE_CREATED;
+GuestViewImpl.prototype.sendCreateRequest = function(
+    createParams, boundCallback) {
+  GuestViewInternal.createGuest(this.viewType, createParams, boundCallback);
 };
 
 // Internal implementation of destroy().
@@ -232,7 +237,7 @@ GuestViewImpl.prototype.destroyImpl = function(callback) {
     return;
   }
 
-  if (this.state == GUEST_STATE_START) {
+  if (this.state == GuestViewImpl.GuestState.GUEST_STATE_START) {
     // destroy() does nothing in this case.
     this.handleCallback(callback);
     return;
@@ -250,7 +255,7 @@ GuestViewImpl.prototype.destroyImpl = function(callback) {
   this.contentWindow = null;
   this.id = 0;
   this.internalInstanceId = 0;
-  this.state = GUEST_STATE_START;
+  this.state = GuestViewImpl.GuestState.GUEST_STATE_START;
   if (ResizeEvent.hasListener(this.callOnResize)) {
     ResizeEvent.removeListener(this.callOnResize);
   }
@@ -269,7 +274,7 @@ GuestViewImpl.prototype.detachImpl = function(callback) {
       this.handleCallback.bind(this, callback));
 
   this.internalInstanceId = 0;
-  this.state = GUEST_STATE_CREATED;
+  this.state = GuestViewImpl.GuestState.GUEST_STATE_CREATED;
 };
 
 // Internal implementation of setSize().
@@ -295,7 +300,7 @@ function GuestView(viewType, guestInstanceId) {
 GuestView.prototype.attach = function(
     internalInstanceId, viewInstanceId, attachParams, callback) {
   var internal = privates(this).internal;
-  internal.actionQueue.push(internal.attachImpl.bind(
+  internal.actionQueue.push(internal.attachImpl$.bind(
       internal, internalInstanceId, viewInstanceId, attachParams, callback));
   internal.performNextAction();
 };
@@ -303,7 +308,7 @@ GuestView.prototype.attach = function(
 // Creates the guestview.
 GuestView.prototype.create = function(createParams, callback) {
   var internal = privates(this).internal;
-  internal.actionQueue.push(internal.createImpl.bind(
+  internal.actionQueue.push(internal.createImpl$.bind(
       internal, createParams, callback));
   internal.performNextAction();
 };
@@ -346,3 +351,5 @@ GuestView.prototype.getId = function() {
 
 // Exports
 exports.GuestView = GuestView;
+exports.GuestViewImpl = GuestViewImpl;
+exports.ResizeEvent = ResizeEvent;

extensions/renderer/resources/guest_view/guest_view_container.js

@@ -23,10 +23,10 @@ function GuestViewContainer(element, viewType) {
   this.guest = new GuestView(viewType);
   this.setupAttributes();
 
-  privates(this).browserPluginElement = this.createBrowserPluginElement();
+  privates(this).internalElement = this.createInternalElement$();
   this.setupFocusPropagation();
   var shadowRoot = this.element.createShadowRoot();
-  shadowRoot.appendChild(privates(this).browserPluginElement);
+  shadowRoot.appendChild(privates(this).internalElement);
 
   GuestViewInternalNatives.RegisterView(this.viewInstanceId, this);
 }
@@ -52,8 +52,7 @@ GuestViewContainer.registerElement = function(guestViewContainerType) {
     if (document.readyState == 'loading')
       return;
 
-    registerBrowserPluginElement(
-        guestViewContainerType.VIEW_TYPE.toLowerCase());
+    registerInternalElement(guestViewContainerType.VIEW_TYPE.toLowerCase());
     registerGuestViewElement(guestViewContainerType);
     window.removeEventListener(event.type, listener, useCapture);
   }, useCapture);
@@ -85,7 +84,7 @@ GuestViewContainer.prototype.setupGuestProperty = function() {
   });
 };
 
-GuestViewContainer.prototype.createBrowserPluginElement = function() {
+GuestViewContainer.prototype.createInternalElement$ = function() {
   // We create BrowserPlugin as a custom element in order to observe changes
   // to attributes synchronously.
   var browserPluginElement =
@@ -104,15 +103,15 @@ GuestViewContainer.prototype.setupFocusPropagation = function() {
   }
   this.element.addEventListener('focus', this.weakWrapper(function(e) {
     // Focus the BrowserPlugin when the GuestViewContainer takes focus.
-    privates(this).browserPluginElement.focus();
+    privates(this).internalElement.focus();
   }));
   this.element.addEventListener('blur', this.weakWrapper(function(e) {
     // Blur the BrowserPlugin when the GuestViewContainer loses focus.
-    privates(this).browserPluginElement.blur();
+    privates(this).internalElement.blur();
   }));
 };
 
-GuestViewContainer.prototype.attachWindow = function() {
+GuestViewContainer.prototype.attachWindow$ = function() {
   if (!this.internalInstanceId) {
     return true;
   }
@@ -129,24 +128,28 @@ GuestViewContainer.prototype.makeGCOwnContainer = function(internalInstanceId) {
   }, -1);
 };
 
-GuestViewContainer.prototype.handleBrowserPluginAttributeMutation =
-    function(name, oldValue, newValue) {
-  if (name == 'internalinstanceid' && !oldValue && !!newValue) {
-    privates(this).browserPluginElement.removeAttribute('internalinstanceid');
-    this.internalInstanceId = parseInt(newValue);
+GuestViewContainer.prototype.onInternalInstanceId = function(
+    internalInstanceId) {
+  this.internalInstanceId = internalInstanceId;
+  this.makeGCOwnContainer(this.internalInstanceId);
 
-    this.makeGCOwnContainer(this.internalInstanceId);
+  // Track when the element resizes using the element resize callback.
+  GuestViewInternalNatives.RegisterElementResizeCallback(
+      this.internalInstanceId, this.weakWrapper(this.onElementResize));
 
-    // Track when the element resizes using the element resize callback.
-    GuestViewInternalNatives.RegisterElementResizeCallback(
-        this.internalInstanceId, this.weakWrapper(this.onElementResize));
+  if (!this.guest.getId()) {
+    return;
+  }
+  this.guest.attach(this.internalInstanceId,
+                    this.viewInstanceId,
+                    this.buildParams());
+};
 
-    if (!this.guest.getId()) {
-      return;
-    }
-    this.guest.attach(this.internalInstanceId,
-                      this.viewInstanceId,
-                      this.buildParams());
+GuestViewContainer.prototype.handleInternalElementAttributeMutation =
+    function(name, oldValue, newValue) {
+  if (name == 'internalinstanceid' && !oldValue && !!newValue) {
+    privates(this).internalElement.removeAttribute('internalinstanceid');
+    this.onInternalInstanceId(parseInt(newValue));
   }
 };
 
@@ -196,7 +199,7 @@ 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) {
+function registerInternalElement(viewType) {
   var proto = $Object.create(HTMLElement.prototype);
 
   proto.createdCallback = function() {
@@ -216,7 +219,7 @@ function registerBrowserPluginElement(viewType) {
     if (!internal) {
       return;
     }
-    internal.handleBrowserPluginAttributeMutation(name, oldValue, newValue);
+    internal.handleInternalElementAttributeMutation(name, oldValue, newValue);
   };
 
   GuestViewContainer[viewType + 'BrowserPlugin'] =

extensions/renderer/resources/guest_view/guest_view_iframe.js

+// Copyright 2015 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.
+
+// --site-per-process overrides for guest_view.js.
+
+var GuestView = require('guestView').GuestView;
+var GuestViewImpl = require('guestView').GuestViewImpl;
+var GuestViewInternalNatives = requireNative('guest_view_internal');
+var ResizeEvent = require('guestView').ResizeEvent;
+
+var getIframeContentWindow = function(viewInstanceId) {
+  var view = GuestViewInternalNatives.GetViewFromID(viewInstanceId);
+  if (!view)
+    return null;
+
+  var internalIframeElement = privates(view).internalElement;
+  if (internalIframeElement)
+    return internalIframeElement.contentWindow;
+
+  return null;
+};
+
+// Internal implementation of attach().
+GuestViewImpl.prototype.attachImpl$ = function(
+    internalInstanceId, viewInstanceId, attachParams, callback) {
+  // Check the current state.
+  if (!this.checkState('attach')) {
+    this.handleCallback(callback);
+    return;
+  }
+
+  // Callback wrapper function to store the contentWindow from the attachGuest()
+  // callback, handle potential attaching failure, register an automatic detach,
+  // and advance the queue.
+  var callbackWrapper = function(callback, contentWindow) {
+    // Check if attaching failed.
+    contentWindow = getIframeContentWindow(viewInstanceId);
+    if (!contentWindow) {
+      this.state = GuestViewImpl.GuestState.GUEST_STATE_CREATED;
+      this.internalInstanceId = 0;
+    } else {
+      // Only update the contentWindow if attaching is successful.
+      this.contentWindow = contentWindow;
+    }
+
+    this.handleCallback(callback);
+  };
+
+  attachParams['instanceId'] = viewInstanceId;
+  var contentWindow = getIframeContentWindow(viewInstanceId);
+  // TODO(lazyboy): Call binding function to attach this guest.
+  // |contentWindow| should be used to retrieve the RenderFrame in cpp.
+
+  this.internalInstanceId = internalInstanceId;
+  this.state = GuestViewImpl.GuestState.GUEST_STATE_ATTACHED;
+
+  // Detach automatically when the container is destroyed.
+  GuestViewInternalNatives.RegisterDestructionCallback(
+      internalInstanceId, this.weakWrapper(function() {
+    if (this.state != GuestViewImpl.GuestState.GUEST_STATE_ATTACHED ||
+        this.internalInstanceId != internalInstanceId) {
+      return;
+    }
+
+    this.internalInstanceId = 0;
+    this.state = GuestViewImpl.GuestState.GUEST_STATE_CREATED;
+  }, viewInstanceId));
+};
+
+// Internal implementation of create().
+GuestViewImpl.prototype.createImpl$ = function(createParams, callback) {
+  // Check the current state.
+  if (!this.checkState('create')) {
+    this.handleCallback(callback);
+    return;
+  }
+
+  // Callback wrapper function to store the guestInstanceId from the
+  // createGuest() callback, handle potential creation failure, and advance the
+  // queue.
+  var callbackWrapper = function(callback, guestInfo) {
+    this.id = guestInfo.id;
+
+    // Check if creation failed.
+    if (this.id === 0) {
+      this.state = GuestViewImpl.GuestState.GUEST_STATE_START;
+      this.contentWindow = null;
+    }
+
+    ResizeEvent.addListener(this.callOnResize, {instanceId: this.id});
+    this.handleCallback(callback);
+  };
+
+  this.sendCreateRequest(createParams, callbackWrapper.bind(this, callback));
+
+  this.state = GuestViewImpl.GuestState.GUEST_STATE_CREATED;
+};

extensions/renderer/resources/guest_view/guest_view_iframe_container.js

+// Copyright 2015 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.
+
+// --site-per-process overrides for guest_view_container.js
+
+var GuestViewContainer = require('guestViewContainer').GuestViewContainer;
+
+GuestViewContainer.prototype.createInternalElement$ = function() {
+  var iframeElement = document.createElement('iframe');
+  iframeElement.style.width = '100%';
+  iframeElement.style.height = '100%';
+  privates(iframeElement).internal = this;
+  return iframeElement;
+};

extensions/renderer/resources/guest_view/surface_view/surface_view.js

@@ -42,7 +42,7 @@ SurfaceViewImpl.prototype.connect = function(url, callback) {
   this.guest.destroy();
 
   this.guest.create(this.buildParams(), function() {
-    this.attachWindow();
+    this.attachWindow$();
     if (callback) {
       callback(true);
     }

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

@@ -137,7 +137,7 @@ WebViewImpl.prototype.onSizeChanged = function(webViewEvent) {
 
 WebViewImpl.prototype.createGuest = function() {
   this.guest.create(this.buildParams(), function() {
-    this.attachWindow();
+    this.attachWindow$();
   }.bind(this));
 };
 
@@ -178,7 +178,7 @@ WebViewImpl.prototype.buildContainerParams = function() {
   return params;
 };
 
-WebViewImpl.prototype.attachWindow = function(opt_guestInstanceId) {
+WebViewImpl.prototype.attachWindow$ = function(opt_guestInstanceId) {
   // If |opt_guestInstanceId| was provided, then a different existing guest is
   // being attached to this webview, and the current one will get destroyed.
   if (opt_guestInstanceId) {
@@ -189,7 +189,7 @@ WebViewImpl.prototype.attachWindow = function(opt_guestInstanceId) {
     this.guest = new GuestView('webview', opt_guestInstanceId);
   }
 
-  return GuestViewContainer.prototype.attachWindow.call(this);
+  return GuestViewContainer.prototype.attachWindow$.call(this);
 };
 
 // Shared implementation of executeScript() and insertCSS().

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

@@ -163,7 +163,7 @@ NewWindow.prototype.getInterfaceObject = function() {
         webViewImpl.onAttach(this.event.partition);
       }
 
-      var attached = webViewImpl.attachWindow(this.event.windowId);
+      var attached = webViewImpl.attachWindow$(this.event.windowId);
       if (!attached) {
         window.console.error(ERROR_MSG_NEWWINDOW_UNABLE_TO_ATTACH);
       }

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

+// Copyright 2015 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 provides --site-per-process overrides for WebView (<webview>).
+// See web_view.js for details.
+
+var IdGenerator = requireNative('id_generator');
+var WebViewImpl = require('webView').WebViewImpl;
+// NOTE: Do not remove these, we implicitly depend on these in
+// --site-per-process.
+var GuestViewIframe = require('guestViewIframe');
+var GuestViewIframeContainer = require('guestViewIframeContainer');
+
+WebViewImpl.prototype.attachWindow$ = function(opt_guestInstanceId) {
+  // If |opt_guestInstanceId| was provided, then a different existing guest is
+  // being attached to this webview, and the current one will get destroyed.
+  if (opt_guestInstanceId) {
+    if (this.guest.getId() == opt_guestInstanceId) {
+      return true;
+    }
+    this.guest.destroy();
+    this.guest = new GuestView('webview', opt_guestInstanceId);
+  }
+
+  var generatedId = IdGenerator.GetNextId();
+  // Generate an instance id for the container.
+  this.onInternalInstanceId(generatedId);
+  return true;
+};