Unrevert "Sky: When an iframe element is removed, delete its mojo View."

sky/engine/core/html/HTMLIFrameElement.cpp

 // Copyright 2014 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.
 
 #include "config.h"
 #include "core/html/HTMLIFrameElement.h"
 
 #include "gen/sky/core/HTMLNames.h"
 #include "core/frame/LocalFrame.h"
 #include "core/html/parser/HTMLParserIdioms.h"
 #include "core/loader/FrameLoaderClient.h"
 #include "core/rendering/RenderIFrame.h"
 
 namespace blink {
 
 PassRefPtr<HTMLIFrameElement> HTMLIFrameElement::create(Document& document)
 {
     return adoptRef(new HTMLIFrameElement(document));
 }
 
 HTMLIFrameElement::HTMLIFrameElement(Document& document)
     : HTMLElement(HTMLNames::iframeTag, document),
       m_contentView(nullptr)
 {
 }
 
 HTMLIFrameElement::~HTMLIFrameElement()
 {
+    if (m_contentView)
+        m_contentView->RemoveObserver(this);
 }
 
 Node::InsertionNotificationRequest HTMLIFrameElement::insertedInto(ContainerNode* insertionPoint)
 {
     InsertionNotificationRequest result = HTMLElement::insertedInto(insertionPoint);
     if (insertionPoint->inDocument())
         createView();
     return result;
 }
 
 void HTMLIFrameElement::removedFrom(ContainerNode* insertionPoint)
 {
     HTMLElement::removedFrom(insertionPoint);
-    if (insertionPoint->inDocument()) {
-        // TODO(mpcomplete): Tear down the mojo View.
-    }
+    if (m_contentView)
+        m_contentView->Destroy();
 }
 
 RenderObject* HTMLIFrameElement::createRenderer(RenderStyle* style)
 {
     return new RenderIFrame(this);
 }
 
 void HTMLIFrameElement::OnViewDestroyed(mojo::View* view)
 {
     DCHECK_EQ(view, m_contentView);
     m_contentView = nullptr;
 }
 
 void HTMLIFrameElement::createView()
 {
     String urlString = stripLeadingAndTrailingHTMLSpaces(getAttribute(HTMLNames::srcAttr));
     if (urlString.isEmpty())
         urlString = blankURL().string();
 
     LocalFrame* parentFrame = document().frame();
     if (!parentFrame)
         return;
 
     KURL url = document().completeURL(urlString);
     m_contentView = parentFrame->loaderClient()->createChildFrame(url);
+    if (m_contentView)
+        m_contentView->AddObserver(this);
 }
 
 }