Splitting fpdfdoc/doc_* part I

core/fpdfdoc/cpdf_bookmarktree.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 "core/fpdfdoc/include/cpdf_bookmarktree.h"
+
+#include "core/fpdfapi/fpdf_parser/include/cpdf_document.h"
+
+CPDF_Bookmark CPDF_BookmarkTree::GetFirstChild(
+    const CPDF_Bookmark& parent) const {
+  CPDF_Dictionary* pParentDict = parent.GetDict();
+  if (pParentDict)
+    return CPDF_Bookmark(pParentDict->GetDictBy("First"));
+
+  CPDF_Dictionary* pRoot = m_pDocument->GetRoot();
+  if (!pRoot)
+    return CPDF_Bookmark();
+
+  CPDF_Dictionary* pOutlines = pRoot->GetDictBy("Outlines");
+  return pOutlines ? CPDF_Bookmark(pOutlines->GetDictBy("First"))
+                   : CPDF_Bookmark();
+}
+
+CPDF_Bookmark CPDF_BookmarkTree::GetNextSibling(
+    const CPDF_Bookmark& bookmark) const {
+  CPDF_Dictionary* pDict = bookmark.GetDict();
+  if (!pDict)
+    return CPDF_Bookmark();
+
+  CPDF_Dictionary* pNext = pDict->GetDictBy("Next");
+  return pNext == pDict ? CPDF_Bookmark() : CPDF_Bookmark(pNext);
+}