Refactoring: Simplify DocumentWriter by reorganizing its lifetime.

Source/core/testing/MockPagePopupDriver.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 55 matching lines @@
     m_iframe->setInlineStyleProperty(CSSPropertyPosition, CSSValueAbsolute);
     m_iframe->setInlineStyleProperty(CSSPropertyLeft, originBoundsInRootView.x(), CSSPrimitiveValue::CSS_PX, true);
     m_iframe->setInlineStyleProperty(CSSPropertyTop, originBoundsInRootView.maxY(), CSSPrimitiveValue::CSS_PX, true);
     if (document->body())
         document->body()->appendChild(m_iframe.get());
     Frame* contentFrame = m_iframe->contentFrame();
     DocumentWriter* writer = contentFrame->loader()->activeDocumentLoader()->beginWriting("text/html", "UTF-8");
     const char scriptToSetUpPagePopupController[] = "<script>window.pagePopupController = parent.internals.pagePopupController;</script>";
     writer->addData(scriptToSetUpPagePopupController, sizeof(scriptToSetUpPagePopupController));
     m_popupClient->writeDocument(*writer);
-    writer->end();
+    contentFrame->loader()->activeDocumentLoader()->endWriting(writer);
 }
 
 PassRefPtr<MockPagePopup> MockPagePopup::create(PagePopupClient* client, const IntRect& originBoundsInRootView, Frame* mainFrame)
 {
     return adoptRef(new MockPagePopup(client, originBoundsInRootView, mainFrame));
 }
 
 void MockPagePopup::closeLater()
 {
     ref();
@@ skipping 45 matching lines @@
 {
     if (!popup || popup != m_mockPagePopup.get())
         return;
     m_mockPagePopup->closeLater();
     m_mockPagePopup.clear();
     m_pagePopupController->clearPagePopupClient();
     m_pagePopupController.clear();
 }
 
 }