Clean up CPDF_BookmarkTree.

- Change GetFirstChild() and GetNextSibling() to take a const-ref
  parameter.
- Remove unused GetDocument().
- Change all variables to Chromium style.
- Fix a nit by flipping the logic of a comparison.

Change-Id: If4a69eea49b6fddb38ff1f4d6c5e2115b775d4bd
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/79301
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>

core/fpdfdoc/cpdf_bookmarktree.cpp

diff --git a/core/fpdfdoc/cpdf_bookmarktree.cpp b/core/fpdfdoc/cpdf_bookmarktree.cpp
index 5c4fffe..175e925 100644
--- a/core/fpdfdoc/cpdf_bookmarktree.cpp
+++ b/core/fpdfdoc/cpdf_bookmarktree.cpp
@@ -9,29 +9,31 @@
 #include "core/fpdfapi/parser/cpdf_dictionary.h"
 #include "core/fpdfapi/parser/cpdf_document.h"
 
-CPDF_BookmarkTree::CPDF_BookmarkTree(CPDF_Document* pDoc) : m_pDocument(pDoc) {}
+CPDF_BookmarkTree::CPDF_BookmarkTree(CPDF_Document* doc) : document_(doc) {}
 
 CPDF_BookmarkTree::~CPDF_BookmarkTree() = default;
 
-CPDF_Bookmark CPDF_BookmarkTree::GetFirstChild(CPDF_Bookmark* parent) const {
-  const CPDF_Dictionary* pParentDict = parent->GetDict();
-  if (pParentDict)
-    return CPDF_Bookmark(pParentDict->GetDictFor("First"));
+CPDF_Bookmark CPDF_BookmarkTree::GetFirstChild(
+    const CPDF_Bookmark& parent) const {
+  const CPDF_Dictionary* parent_dict = parent.GetDict();
+  if (parent_dict)
+    return CPDF_Bookmark(parent_dict->GetDictFor("First"));
 
-  CPDF_Dictionary* pRoot = m_pDocument->GetRoot();
-  if (!pRoot)
+  const CPDF_Dictionary* root = document_->GetRoot();
+  if (!root)
     return CPDF_Bookmark();
 
-  CPDF_Dictionary* pOutlines = pRoot->GetDictFor("Outlines");
-  return pOutlines ? CPDF_Bookmark(pOutlines->GetDictFor("First"))
-                   : CPDF_Bookmark();
+  const CPDF_Dictionary* outlines = root->GetDictFor("Outlines");
+  return outlines ? CPDF_Bookmark(outlines->GetDictFor("First"))
+                  : CPDF_Bookmark();
 }
 
-CPDF_Bookmark CPDF_BookmarkTree::GetNextSibling(CPDF_Bookmark* bookmark) const {
-  const CPDF_Dictionary* pDict = bookmark->GetDict();
-  if (!pDict)
+CPDF_Bookmark CPDF_BookmarkTree::GetNextSibling(
+    const CPDF_Bookmark& bookmark) const {
+  const CPDF_Dictionary* dict = bookmark.GetDict();
+  if (!dict)
     return CPDF_Bookmark();
 
-  const CPDF_Dictionary* pNext = pDict->GetDictFor("Next");
-  return pNext == pDict ? CPDF_Bookmark() : CPDF_Bookmark(pNext);
+  const CPDF_Dictionary* next = dict->GetDictFor("Next");
+  return next != dict ? CPDF_Bookmark(next) : CPDF_Bookmark();
 }

core/fpdfdoc/cpdf_bookmarktree.h

diff --git a/core/fpdfdoc/cpdf_bookmarktree.h b/core/fpdfdoc/cpdf_bookmarktree.h
index b374bfa..6cadbb7 100644
--- a/core/fpdfdoc/cpdf_bookmarktree.h
+++ b/core/fpdfdoc/cpdf_bookmarktree.h
@@ -14,15 +14,14 @@
 
 class CPDF_BookmarkTree {
  public:
-  explicit CPDF_BookmarkTree(CPDF_Document* pDoc);
+  explicit CPDF_BookmarkTree(CPDF_Document* doc);
   ~CPDF_BookmarkTree();
 
-  CPDF_Bookmark GetFirstChild(CPDF_Bookmark* parent) const;
-  CPDF_Bookmark GetNextSibling(CPDF_Bookmark* bookmark) const;
-  CPDF_Document* GetDocument() const { return m_pDocument.Get(); }
+  CPDF_Bookmark GetFirstChild(const CPDF_Bookmark& parent) const;
+  CPDF_Bookmark GetNextSibling(const CPDF_Bookmark& bookmark) const;
 
  private:
-  UnownedPtr<CPDF_Document> const m_pDocument;
+  UnownedPtr<CPDF_Document> const document_;
 };
 
 #endif  // CORE_FPDFDOC_CPDF_BOOKMARKTREE_H_

fpdfsdk/fpdf_doc.cpp

diff --git a/fpdfsdk/fpdf_doc.cpp b/fpdfsdk/fpdf_doc.cpp
index 83d9a4a..551918f 100644
--- a/fpdfsdk/fpdf_doc.cpp
+++ b/fpdfsdk/fpdf_doc.cpp
@@ -48,13 +48,13 @@
   }
 
   // Go into children items.
-  CPDF_Bookmark child = tree.GetFirstChild(&bookmark);
+  CPDF_Bookmark child = tree.GetFirstChild(bookmark);
   while (child.GetDict() && !pdfium::Contains(*visited, child.GetDict())) {
     // Check this item and its children.
     CPDF_Bookmark found = FindBookmark(tree, child, title, visited);
     if (found.GetDict())
       return found;
-    child = tree.GetNextSibling(&child);
+    child = tree.GetNextSibling(child);
   }
   return CPDF_Bookmark();
 }
@@ -81,7 +81,7 @@
   CPDF_BookmarkTree tree(pDoc);
   CPDF_Bookmark cBookmark(CPDFDictionaryFromFPDFBookmark(bookmark));
   return FPDFBookmarkFromCPDFDictionary(
-      tree.GetFirstChild(&cBookmark).GetDict());
+      tree.GetFirstChild(cBookmark).GetDict());
 }
 
 FPDF_EXPORT FPDF_BOOKMARK FPDF_CALLCONV
@@ -96,7 +96,7 @@
   CPDF_BookmarkTree tree(pDoc);
   CPDF_Bookmark cBookmark(CPDFDictionaryFromFPDFBookmark(bookmark));
   return FPDFBookmarkFromCPDFDictionary(
-      tree.GetNextSibling(&cBookmark).GetDict());
+      tree.GetNextSibling(cBookmark).GetDict());
 }
 
 FPDF_EXPORT unsigned long FPDF_CALLCONV