Move GetNativeCharSet() into an anonymous namespace.

Move CPDF_InteractiveForm::GetNativeCharSet() into an anonymous
namespace. Also remove one of the two variants of AddNativeFont(),
which is just a wrapper around the other, and remove a now redundant
GetNativeCharSet() call.

Change-Id: I5882948667b9e6d1982dda0d64ffd2e637fa2de9
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/73118
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Hui Yingst <nigi@chromium.org>

core/fpdfdoc/cpdf_interactiveform.cpp

diff --git a/core/fpdfdoc/cpdf_interactiveform.cpp b/core/fpdfdoc/cpdf_interactiveform.cpp
index 27fa31c..ee5670b 100644
--- a/core/fpdfdoc/cpdf_interactiveform.cpp
+++ b/core/fpdfdoc/cpdf_interactiveform.cpp
@@ -148,6 +148,10 @@
   return csTmp;
 }
 
+uint8_t GetNativeCharSet() {
+  return FX_GetCharsetFromCodePage(FXSYS_GetACP());
+}
+
 void InitDict(CPDF_Dictionary*& pFormDict, CPDF_Document* pDocument) {
   if (!pDocument)
     return;
@@ -161,7 +165,7 @@
   ByteString csDA;
   if (!pFormDict->KeyExist("DR")) {
     ByteString csBaseName;
-    uint8_t charSet = CPDF_InteractiveForm::GetNativeCharSet();
+    uint8_t charSet = GetNativeCharSet();
     RetainPtr<CPDF_Font> pFont = CPDF_InteractiveForm::AddStandardFont(
         pDocument, CFX_Font::kDefaultAnsiFontName);
     if (pFont)
@@ -170,7 +174,7 @@
     if (charSet != FX_CHARSET_ANSI) {
       ByteString csFontName = GetNativeFontName(charSet, nullptr);
       if (!pFont || csFontName != CFX_Font::kDefaultAnsiFontName) {
-        pFont = CPDF_InteractiveForm::AddNativeFont(pDocument);
+        pFont = CPDF_InteractiveForm::AddNativeFont(charSet, pDocument);
         if (pFont) {
           csBaseName.clear();
           AddFont(pFormDict, pDocument, pFont, &csBaseName);
@@ -542,7 +546,7 @@
   if (!pFormDict)
     InitDict(pFormDict, pDocument);
 
-  uint8_t charSet = CPDF_InteractiveForm::GetNativeCharSet();
+  uint8_t charSet = GetNativeCharSet();
   ByteString csTemp;
   RetainPtr<CPDF_Font> pFont =
       GetNativeFont(pFormDict, pDocument, charSet, &csTemp);
@@ -563,11 +567,6 @@
   return pFont;
 }
 
-// static
-uint8_t CPDF_InteractiveForm::GetNativeCharSet() {
-  return FX_GetCharsetFromCodePage(FXSYS_GetACP());
-}
-
 CPDF_InteractiveForm::CPDF_InteractiveForm(CPDF_Document* pDocument)
     : m_pDocument(pDocument), m_pFieldTree(std::make_unique<CFieldTree>()) {
   CPDF_Dictionary* pRoot = m_pDocument->GetRoot();
@@ -630,11 +629,6 @@
   return nullptr;
 }
 
-RetainPtr<CPDF_Font> CPDF_InteractiveForm::AddNativeFont(
-    CPDF_Document* pDocument) {
-  return pDocument ? AddNativeFont(GetNativeCharSet(), pDocument) : nullptr;
-}
-
 size_t CPDF_InteractiveForm::CountFields(const WideString& csFieldName) const {
   if (csFieldName.IsEmpty())
     return m_pFieldTree->m_Root.CountFields();

core/fpdfdoc/cpdf_interactiveform.h

diff --git a/core/fpdfdoc/cpdf_interactiveform.h b/core/fpdfdoc/cpdf_interactiveform.h
index e76f419..e4e8f42 100644
--- a/core/fpdfdoc/cpdf_interactiveform.h
+++ b/core/fpdfdoc/cpdf_interactiveform.h
@@ -49,12 +49,10 @@
 
   static void SetUpdateAP(bool bUpdateAP);
   static bool IsUpdateAPEnabled();
-  static uint8_t GetNativeCharSet();
   static RetainPtr<CPDF_Font> AddStandardFont(CPDF_Document* pDocument,
                                               ByteString csFontName);
   static RetainPtr<CPDF_Font> AddNativeFont(uint8_t iCharSet,
                                             CPDF_Document* pDocument);
-  static RetainPtr<CPDF_Font> AddNativeFont(CPDF_Document* pDocument);
   static RetainPtr<CPDF_Font> AddNativeInteractiveFormFont(
       CPDF_Dictionary*& pFormDict,
       CPDF_Document* pDocument,