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

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 ebcc3136b5e56a3b0bb67996f3da111ab60ebb61..cee4d6dd50148e21e51b995482aa14ac2914beb2 100644
--- a/extensions/renderer/resources/guest_view/guest_view_container.js
+++ b/extensions/renderer/resources/guest_view/guest_view_container.js
@@ -22,10 +22,10 @@ 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);
 }
@@ -84,7 +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 =
@@ -103,15 +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;
   }
@@ -122,22 +122,27 @@ GuestViewContainer.prototype.attachWindow = function() {
   return true;
 };
 
+GuestViewContainer.prototype.onInternalInstanceID = function(
+    internalInstanceId) {
+  this.internalInstanceId = internalInstanceId;
+
+  // 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());
+};
+
 GuestViewContainer.prototype.handleBrowserPluginAttributeMutation =
     function(name, oldValue, newValue) {
   if (name == 'internalinstanceid' && !oldValue && !!newValue) {
-    privates(this).browserPluginElement.removeAttribute('internalinstanceid');
-    this.internalInstanceId = parseInt(newValue);
-
-    // 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());
+    privates(this).internalElement.removeAttribute('internalinstanceid');
+    this.onInternalInstanceID(parseInt(newValue));
   }
 };