Rename xfa_doclayout and xfa_document_layout_imp files.

xfa/fxfa/parser/cxfa_layoutitem.cpp

+// Copyright 2016 PDFium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
+
+#include "xfa/fxfa/parser/cxfa_layoutitem.h"
+
+#include "xfa/fxfa/parser/cxfa_containerlayoutitem.h"
+#include "xfa/fxfa/parser/cxfa_contentlayoutitem.h"
+
+CXFA_LayoutItem::CXFA_LayoutItem(CXFA_Node* pNode, FX_BOOL bIsContentLayoutItem)
+    : m_pFormNode(pNode),
+      m_pParent(nullptr),
+      m_pNextSibling(nullptr),
+      m_pFirstChild(nullptr),
+      m_bIsContentLayoutItem(bIsContentLayoutItem) {}
+
+CXFA_LayoutItem::~CXFA_LayoutItem() {}
+
+CXFA_ContainerLayoutItem* CXFA_LayoutItem::AsContainerLayoutItem() {
+  return IsContainerLayoutItem() ? static_cast<CXFA_ContainerLayoutItem*>(this)
+                                 : nullptr;
+}
+CXFA_ContentLayoutItem* CXFA_LayoutItem::AsContentLayoutItem() {
+  return IsContentLayoutItem() ? static_cast<CXFA_ContentLayoutItem*>(this)
+                               : nullptr;
+}