Make WebView use new Custom Element callback names exclusively.

chrome/renderer/resources/extensions/web_view.js

Index: chrome/renderer/resources/extensions/web_view.js
diff --git a/chrome/renderer/resources/extensions/web_view.js b/chrome/renderer/resources/extensions/web_view.js
index d827f3fbe2cda853eaa3dbcd20fcc041967bd1b8..f9db94f3953bb6490aa8f8e0a7bc56b278cb2b9c 100644
--- a/chrome/renderer/resources/extensions/web_view.js
+++ b/chrome/renderer/resources/extensions/web_view.js
@@ -939,10 +939,6 @@ function registerBrowserPluginElement() {
     var unused = this.nonExistentAttribute;
   };
 
-  // TODO(dominicc): Remove this line once Custom Elements renames
-  // enteredViewCallback to attachedCallback
-  proto.enteredViewCallback = proto.attachedCallback;
-
   WebViewInternal.BrowserPlugin =
       DocumentNatives.RegisterElement('browser-plugin', {extends: 'object',
                                                          prototype: proto});
@@ -951,12 +947,6 @@ function registerBrowserPluginElement() {
   delete proto.attachedCallback;
   delete proto.detachedCallback;
   delete proto.attributeChangedCallback;
-
-  // TODO(dominicc): Remove these lines once Custom Elements renames
-  // enteredView, leftView callbacks to attached, detached
-  // respectively.
-  delete proto.enteredViewCallback;
-  delete proto.leftViewCallback;
 }
 
 // Registers <webview> custom element.
@@ -1028,12 +1018,6 @@ function registerWebViewElement() {
   delete proto.attachedCallback;
   delete proto.detachedCallback;
   delete proto.attributeChangedCallback;
-
-  // TODO(dominicc): Remove these lines once Custom Elements renames
-  // enteredView, leftView callbacks to attached, detached
-  // respectively.
-  delete proto.enteredViewCallback;
-  delete proto.leftViewCallback;
 }
 
 var useCapture = true;