Mark numerious pointers as const.

They are mostly CPDF_Object* and derived classes, but others that should
be are marked const as well.

Change-Id: Ib3344d7d8db90940df8edc97c0dd6c59da080541
Reviewed-on: https://pdfium-review.googlesource.com/32180
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>

28 files changed, 161 insertions, 145 deletions

diff --git a/core/fpdfapi/page/cpdf_color.cpp b/core/fpdfapi/page/cpdf_color.cpp
index b3dd141103..44b2e4023d 100644
--- a/core/fpdfapi/page/cpdf_color.cpp
+++ b/core/fpdfapi/page/cpdf_color.cpp
@@ -127,7 +127,7 @@ void CPDF_Color::Copy(const CPDF_Color& src) {
     return;
 
   CPDF_Document* pDoc = m_pCS->GetDocument();
-  CPDF_Array* pArray = m_pCS->GetArray();
+  const CPDF_Array* pArray = m_pCS->GetArray();
   if (pDoc && pArray) {
     m_pCS = pDoc->GetPageData()->GetCopiedColorSpace(pArray);
     if (!m_pCS)
diff --git a/core/fpdfapi/page/cpdf_colorspace.cpp b/core/fpdfapi/page/cpdf_colorspace.cpp
index d7fb18edd7..aa664d4e0f 100644
--- a/core/fpdfapi/page/cpdf_colorspace.cpp
+++ b/core/fpdfapi/page/cpdf_colorspace.cpp
@@ -112,8 +112,8 @@ class CPDF_CalGray : public CPDF_ColorSpace {
 
   // CPDF_ColorSpace:
   uint32_t v_Load(CPDF_Document* pDoc,
-                  CPDF_Array* pArray,
-                  std::set<CPDF_Object*>* pVisited) override;
+                  const CPDF_Array* pArray,
+                  std::set<const CPDF_Object*>* pVisited) override;
   bool GetRGB(const float* pBuf, float* R, float* G, float* B) const override;
   void TranslateImageLine(uint8_t* pDestBuf,
                           const uint8_t* pSrcBuf,
@@ -136,8 +136,8 @@ class CPDF_CalRGB : public CPDF_ColorSpace {
   ~CPDF_CalRGB() override {}
 
   uint32_t v_Load(CPDF_Document* pDoc,
-                  CPDF_Array* pArray,
-                  std::set<CPDF_Object*>* pVisited) override;
+                  const CPDF_Array* pArray,
+                  std::set<const CPDF_Object*>* pVisited) override;
 
   bool GetRGB(const float* pBuf, float* R, float* G, float* B) const override;
 
@@ -166,8 +166,8 @@ class CPDF_LabCS : public CPDF_ColorSpace {
   ~CPDF_LabCS() override {}
 
   uint32_t v_Load(CPDF_Document* pDoc,
-                  CPDF_Array* pArray,
-                  std::set<CPDF_Object*>* pVisited) override;
+                  const CPDF_Array* pArray,
+                  std::set<const CPDF_Object*>* pVisited) override;
 
   void GetDefaultValue(int iComponent,
                        float* value,
@@ -197,8 +197,8 @@ class CPDF_ICCBasedCS : public CPDF_ColorSpace {
 
   // CPDF_ColorSpace:
   uint32_t v_Load(CPDF_Document* pDoc,
-                  CPDF_Array* pArray,
-                  std::set<CPDF_Object*>* pVisited) override;
+                  const CPDF_Array* pArray,
+                  std::set<const CPDF_Object*>* pVisited) override;
   bool GetRGB(const float* pBuf, float* R, float* G, float* B) const override;
   void EnableStdConversion(bool bEnabled) override;
   void TranslateImageLine(uint8_t* pDestBuf,
@@ -213,12 +213,12 @@ class CPDF_ICCBasedCS : public CPDF_ColorSpace {
  private:
   // If no valid ICC profile or using sRGB, try looking for an alternate.
   bool FindAlternateProfile(CPDF_Document* pDoc,
-                            CPDF_Dictionary* pDict,
-                            std::set<CPDF_Object*>* pVisited,
+                            const CPDF_Dictionary* pDict,
+                            std::set<const CPDF_Object*>* pVisited,
                             uint32_t nExpectedComponents);
   static CPDF_ColorSpace* GetStockAlternateProfile(uint32_t nComponents);
   static bool IsValidComponents(int32_t nComps);
-  static std::vector<float> GetRanges(CPDF_Dictionary* pDict,
+  static std::vector<float> GetRanges(const CPDF_Dictionary* pDict,
                                       uint32_t nComponents);
 
   MaybeOwned<CPDF_ColorSpace> m_pAlterCS;
@@ -233,8 +233,8 @@ class CPDF_IndexedCS : public CPDF_ColorSpace {
   ~CPDF_IndexedCS() override;
 
   uint32_t v_Load(CPDF_Document* pDoc,
-                  CPDF_Array* pArray,
-                  std::set<CPDF_Object*>* pVisited) override;
+                  const CPDF_Array* pArray,
+                  std::set<const CPDF_Object*>* pVisited) override;
 
   bool GetRGB(const float* pBuf, float* R, float* G, float* B) const override;
 
@@ -242,7 +242,7 @@ class CPDF_IndexedCS : public CPDF_ColorSpace {
 
  private:
   CPDF_ColorSpace* m_pBaseCS = nullptr;
-  UnownedPtr<CPDF_CountedColorSpace> m_pCountedBaseCS;
+  UnownedPtr<const CPDF_CountedColorSpace> m_pCountedBaseCS;
   uint32_t m_nBaseComponents = 0;
   int m_MaxIndex = 0;
   ByteString m_Table;
@@ -260,14 +260,14 @@ class CPDF_SeparationCS : public CPDF_ColorSpace {
                        float* min,
                        float* max) const override;
   uint32_t v_Load(CPDF_Document* pDoc,
-                  CPDF_Array* pArray,
-                  std::set<CPDF_Object*>* pVisited) override;
+                  const CPDF_Array* pArray,
+                  std::set<const CPDF_Object*>* pVisited) override;
   bool GetRGB(const float* pBuf, float* R, float* G, float* B) const override;
   void EnableStdConversion(bool bEnabled) override;
 
  private:
   std::unique_ptr<CPDF_ColorSpace> m_pAltCS;
-  std::unique_ptr<CPDF_Function> m_pFunc;
+  std::unique_ptr<const CPDF_Function> m_pFunc;
   enum { None, All, Colorant } m_Type;
 };
 
@@ -282,14 +282,14 @@ class CPDF_DeviceNCS : public CPDF_ColorSpace {
                        float* min,
                        float* max) const override;
   uint32_t v_Load(CPDF_Document* pDoc,
-                  CPDF_Array* pArray,
-                  std::set<CPDF_Object*>* pVisited) override;
+                  const CPDF_Array* pArray,
+                  std::set<const CPDF_Object*>* pVisited) override;
   bool GetRGB(const float* pBuf, float* R, float* G, float* B) const override;
   void EnableStdConversion(bool bEnabled) override;
 
  private:
   std::unique_ptr<CPDF_ColorSpace> m_pAltCS;
-  std::unique_ptr<CPDF_Function> m_pFunc;
+  std::unique_ptr<const CPDF_Function> m_pFunc;
 };
 
 class Vector_3by1 {
@@ -437,27 +437,27 @@ CPDF_ColorSpace* CPDF_ColorSpace::GetStockCS(int family) {
 // static
 std::unique_ptr<CPDF_ColorSpace> CPDF_ColorSpace::Load(CPDF_Document* pDoc,
                                                        CPDF_Object* pObj) {
-  std::set<CPDF_Object*> visited;
+  std::set<const CPDF_Object*> visited;
   return Load(pDoc, pObj, &visited);
 }
 
 // static
 std::unique_ptr<CPDF_ColorSpace> CPDF_ColorSpace::Load(
     CPDF_Document* pDoc,
-    CPDF_Object* pObj,
-    std::set<CPDF_Object*>* pVisited) {
+    const CPDF_Object* pObj,
+    std::set<const CPDF_Object*>* pVisited) {
   if (!pObj)
     return nullptr;
 
   if (pdfium::ContainsKey(*pVisited, pObj))
     return nullptr;
 
-  pdfium::ScopedSetInsertion<CPDF_Object*> insertion(pVisited, pObj);
+  pdfium::ScopedSetInsertion<const CPDF_Object*> insertion(pVisited, pObj);
 
   if (pObj->IsName())
     return pdfium::WrapUnique(ColorspaceFromName(pObj->GetString()));
 
-  if (CPDF_Stream* pStream = pObj->AsStream()) {
+  if (const CPDF_Stream* pStream = pObj->AsStream()) {
     CPDF_Dictionary* pDict = pStream->GetDict();
     if (!pDict)
       return nullptr;
@@ -473,11 +473,11 @@ std::unique_ptr<CPDF_ColorSpace> CPDF_ColorSpace::Load(
     return nullptr;
   }
 
-  CPDF_Array* pArray = pObj->AsArray();
+  const CPDF_Array* pArray = pObj->AsArray();
   if (!pArray || pArray->IsEmpty())
     return nullptr;
 
-  CPDF_Object* pFamilyObj = pArray->GetDirectObjectAt(0);
+  const CPDF_Object* pFamilyObj = pArray->GetDirectObjectAt(0);
   if (!pFamilyObj)
     return nullptr;
 
@@ -627,9 +627,9 @@ CPDF_CalGray::CPDF_CalGray(CPDF_Document* pDoc)
     : CPDF_ColorSpace(pDoc, PDFCS_CALGRAY) {}
 
 uint32_t CPDF_CalGray::v_Load(CPDF_Document* pDoc,
-                              CPDF_Array* pArray,
-                              std::set<CPDF_Object*>* pVisited) {
-  CPDF_Dictionary* pDict = pArray->GetDictAt(1);
+                              const CPDF_Array* pArray,
+                              std::set<const CPDF_Object*>* pVisited) {
+  const CPDF_Dictionary* pDict = pArray->GetDictAt(1);
   if (!pDict)
     return 0;
 
@@ -671,9 +671,9 @@ CPDF_CalRGB::CPDF_CalRGB(CPDF_Document* pDoc)
     : CPDF_ColorSpace(pDoc, PDFCS_CALRGB) {}
 
 uint32_t CPDF_CalRGB::v_Load(CPDF_Document* pDoc,
-                             CPDF_Array* pArray,
-                             std::set<CPDF_Object*>* pVisited) {
-  CPDF_Dictionary* pDict = pArray->GetDictAt(1);
+                             const CPDF_Array* pArray,
+                             std::set<const CPDF_Object*>* pVisited) {
+  const CPDF_Dictionary* pDict = pArray->GetDictAt(1);
   if (!pDict)
     return 0;
 
@@ -682,7 +682,7 @@ uint32_t CPDF_CalRGB::v_Load(CPDF_Document* pDoc,
 
   GetBlackPoint(pDict, m_BlackPoint);
 
-  CPDF_Array* pParam = pDict->GetArrayFor("Gamma");
+  const CPDF_Array* pParam = pDict->GetArrayFor("Gamma");
   if (pParam) {
     m_bGamma = true;
     for (size_t i = 0; i < FX_ArraySize(m_Gamma); ++i)
@@ -775,9 +775,9 @@ void CPDF_LabCS::GetDefaultValue(int iComponent,
 }
 
 uint32_t CPDF_LabCS::v_Load(CPDF_Document* pDoc,
-                            CPDF_Array* pArray,
-                            std::set<CPDF_Object*>* pVisited) {
-  CPDF_Dictionary* pDict = pArray->GetDictAt(1);
+                            const CPDF_Array* pArray,
+                            std::set<const CPDF_Object*>* pVisited) {
+  const CPDF_Dictionary* pDict = pArray->GetDictAt(1);
   if (!pDict)
     return 0;
 
@@ -786,7 +786,7 @@ uint32_t CPDF_LabCS::v_Load(CPDF_Document* pDoc,
 
   GetBlackPoint(pDict, m_BlackPoint);
 
-  CPDF_Array* pParam = pDict->GetArrayFor("Range");
+  const CPDF_Array* pParam = pDict->GetArrayFor("Range");
   static constexpr float kDefaultRanges[kRangesCount] = {-100.0f, 100.0f,
                                                          -100.0f, 100.0f};
   static_assert(FX_ArraySize(kDefaultRanges) == FX_ArraySize(m_Ranges),
@@ -863,8 +863,8 @@ CPDF_ICCBasedCS::~CPDF_ICCBasedCS() {
 }
 
 uint32_t CPDF_ICCBasedCS::v_Load(CPDF_Document* pDoc,
-                                 CPDF_Array* pArray,
-                                 std::set<CPDF_Object*>* pVisited) {
+                                 const CPDF_Array* pArray,
+                                 std::set<const CPDF_Object*>* pVisited) {
   CPDF_Stream* pStream = pArray->GetStreamAt(1);
   if (!pStream)
     return 0;
@@ -872,7 +872,7 @@ uint32_t CPDF_ICCBasedCS::v_Load(CPDF_Document* pDoc,
   // The PDF 1.7 spec says the number of components must be valid. While some
   // PDF viewers tolerate invalid values, Acrobat does not, so be consistent
   // with Acrobat and reject bad values.
-  CPDF_Dictionary* pDict = pStream->GetDict();
+  const CPDF_Dictionary* pDict = pStream->GetDict();
   int32_t nDictComponents = pDict ? pDict->GetIntegerFor("N") : 0;
   if (!IsValidComponents(nDictComponents))
     return 0;
@@ -1010,11 +1010,12 @@ void CPDF_ICCBasedCS::TranslateImageLine(uint8_t* pDestBuf,
   }
 }
 
-bool CPDF_ICCBasedCS::FindAlternateProfile(CPDF_Document* pDoc,
-                                           CPDF_Dictionary* pDict,
-                                           std::set<CPDF_Object*>* pVisited,
-                                           uint32_t nExpectedComponents) {
-  CPDF_Object* pAlterCSObj = pDict->GetDirectObjectFor("Alternate");
+bool CPDF_ICCBasedCS::FindAlternateProfile(
+    CPDF_Document* pDoc,
+    const CPDF_Dictionary* pDict,
+    std::set<const CPDF_Object*>* pVisited,
+    uint32_t nExpectedComponents) {
+  const CPDF_Object* pAlterCSObj = pDict->GetDirectObjectFor("Alternate");
   if (!pAlterCSObj)
     return false;
 
@@ -1051,13 +1052,13 @@ bool CPDF_ICCBasedCS::IsValidComponents(int32_t nComps) {
 }
 
 // static
-std::vector<float> CPDF_ICCBasedCS::GetRanges(CPDF_Dictionary* pDict,
+std::vector<float> CPDF_ICCBasedCS::GetRanges(const CPDF_Dictionary* pDict,
                                               uint32_t nComponents) {
   ASSERT(IsValidComponents(nComponents));
 
   std::vector<float> ranges;
   ranges.reserve(nComponents * 2);
-  CPDF_Array* pRanges = pDict->GetArrayFor("Range");
+  const CPDF_Array* pRanges = pDict->GetArrayFor("Range");
   if (pRanges) {
     for (uint32_t i = 0; i < nComponents * 2; i++) {
       ranges.push_back(pRanges->GetNumberAt(i));
@@ -1076,7 +1077,8 @@ CPDF_IndexedCS::CPDF_IndexedCS(CPDF_Document* pDoc)
 
 CPDF_IndexedCS::~CPDF_IndexedCS() {
   FX_Free(m_pCompMinMax);
-  CPDF_ColorSpace* pCS = m_pCountedBaseCS ? m_pCountedBaseCS->get() : nullptr;
+  const CPDF_ColorSpace* pCS =
+      m_pCountedBaseCS ? m_pCountedBaseCS->get() : nullptr;
   if (pCS && m_pDocument) {
     auto* pPageData = m_pDocument->GetPageData();
     if (pPageData)
@@ -1085,12 +1087,12 @@ CPDF_IndexedCS::~CPDF_IndexedCS() {
 }
 
 uint32_t CPDF_IndexedCS::v_Load(CPDF_Document* pDoc,
-                                CPDF_Array* pArray,
-                                std::set<CPDF_Object*>* pVisited) {
+                                const CPDF_Array* pArray,
+                                std::set<const CPDF_Object*>* pVisited) {
   if (pArray->GetCount() < 4)
     return 0;
 
-  CPDF_Object* pBaseObj = pArray->GetDirectObjectAt(1);
+  const CPDF_Object* pBaseObj = pArray->GetDirectObjectAt(1);
   if (pBaseObj == m_pArray)
     return 0;
 
@@ -1181,8 +1183,8 @@ void CPDF_SeparationCS::GetDefaultValue(int iComponent,
 }
 
 uint32_t CPDF_SeparationCS::v_Load(CPDF_Document* pDoc,
-                                   CPDF_Array* pArray,
-                                   std::set<CPDF_Object*>* pVisited) {
+                                   const CPDF_Array* pArray,
+                                   std::set<const CPDF_Object*>* pVisited) {
   ByteString name = pArray->GetStringAt(1);
   if (name == "None") {
     m_Type = None;
@@ -1190,7 +1192,7 @@ uint32_t CPDF_SeparationCS::v_Load(CPDF_Document* pDoc,
   }
 
   m_Type = Colorant;
-  CPDF_Object* pAltCS = pArray->GetDirectObjectAt(2);
+  const CPDF_Object* pAltCS = pArray->GetDirectObjectAt(2);
   if (pAltCS == m_pArray)
     return 0;
 
@@ -1201,7 +1203,7 @@ uint32_t CPDF_SeparationCS::v_Load(CPDF_Document* pDoc,
   if (m_pAltCS->IsSpecial())
     return 0;
 
-  CPDF_Object* pFuncObj = pArray->GetDirectObjectAt(3);
+  const CPDF_Object* pFuncObj = pArray->GetDirectObjectAt(3);
   if (pFuncObj && !pFuncObj->IsName()) {
     auto pFunc = CPDF_Function::Load(pFuncObj);
     if (pFunc && pFunc->CountOutputs() >= m_pAltCS->CountComponents())
@@ -1252,13 +1254,13 @@ void CPDF_DeviceNCS::GetDefaultValue(int iComponent,
 }
 
 uint32_t CPDF_DeviceNCS::v_Load(CPDF_Document* pDoc,
-                                CPDF_Array* pArray,
-                                std::set<CPDF_Object*>* pVisited) {
-  CPDF_Array* pObj = ToArray(pArray->GetDirectObjectAt(1));
+                                const CPDF_Array* pArray,
+                                std::set<const CPDF_Object*>* pVisited) {
+  const CPDF_Array* pObj = ToArray(pArray->GetDirectObjectAt(1));
   if (!pObj)
     return 0;
 
-  CPDF_Object* pAltCS = pArray->GetDirectObjectAt(2);
+  const CPDF_Object* pAltCS = pArray->GetDirectObjectAt(2);
   if (!pAltCS || pAltCS == m_pArray)
     return 0;
 
diff --git a/core/fpdfapi/page/cpdf_colorspace.h b/core/fpdfapi/page/cpdf_colorspace.h
index 71722224aa..fba63917f7 100644
--- a/core/fpdfapi/page/cpdf_colorspace.h
+++ b/core/fpdfapi/page/cpdf_colorspace.h
@@ -49,8 +49,8 @@ class CPDF_ColorSpace {
                                                CPDF_Object* pCSObj);
   static std::unique_ptr<CPDF_ColorSpace> Load(
       CPDF_Document* pDoc,
-      CPDF_Object* pCSObj,
-      std::set<CPDF_Object*>* pVisited);
+      const CPDF_Object* pCSObj,
+      std::set<const CPDF_Object*>* pVisited);
 
   void Release();
 
@@ -97,7 +97,7 @@ class CPDF_ColorSpace {
                              float* G,
                              float* B) const;
 
-  CPDF_Array* GetArray() const { return m_pArray.Get(); }
+  const CPDF_Array* GetArray() const { return m_pArray.Get(); }
   CPDF_Document* GetDocument() const { return m_pDocument.Get(); }
 
  protected:
@@ -106,15 +106,15 @@ class CPDF_ColorSpace {
 
   // Returns the number of components, or 0 on failure.
   virtual uint32_t v_Load(CPDF_Document* pDoc,
-                          CPDF_Array* pArray,
-                          std::set<CPDF_Object*>* pVisited) = 0;
+                          const CPDF_Array* pArray,
+                          std::set<const CPDF_Object*>* pVisited) = 0;
 
   // Stock colorspaces are not loaded normally. This initializes their
   // components count.
   void SetComponentsForStockCS(uint32_t nComponents);
 
   UnownedPtr<CPDF_Document> const m_pDocument;
-  UnownedPtr<CPDF_Array> m_pArray;
+  UnownedPtr<const CPDF_Array> m_pArray;
   const int m_Family;
   uint32_t m_dwStdConversion = 0;
 
diff --git a/core/fpdfapi/page/cpdf_devicecs.cpp b/core/fpdfapi/page/cpdf_devicecs.cpp
index bf9b3768e7..dd440f5398 100644
--- a/core/fpdfapi/page/cpdf_devicecs.cpp
+++ b/core/fpdfapi/page/cpdf_devicecs.cpp
@@ -63,8 +63,8 @@ CPDF_DeviceCS::CPDF_DeviceCS(int family) : CPDF_ColorSpace(nullptr, family) {
 CPDF_DeviceCS::~CPDF_DeviceCS() {}
 
 uint32_t CPDF_DeviceCS::v_Load(CPDF_Document* pDoc,
-                               CPDF_Array* pArray,
-                               std::set<CPDF_Object*>* pVisited) {
+                               const CPDF_Array* pArray,
+                               std::set<const CPDF_Object*>* pVisited) {
   // Unlike other classes that inherit from CPDF_ColorSpace, CPDF_DeviceCS is
   // never loaded by CPDF_ColorSpace.
   NOTREACHED();
diff --git a/core/fpdfapi/page/cpdf_devicecs.h b/core/fpdfapi/page/cpdf_devicecs.h
index aecda71a41..bf668c359b 100644
--- a/core/fpdfapi/page/cpdf_devicecs.h
+++ b/core/fpdfapi/page/cpdf_devicecs.h
@@ -18,8 +18,8 @@ class CPDF_DeviceCS : public CPDF_ColorSpace {
 
   // CPDF_ColorSpace:
   uint32_t v_Load(CPDF_Document* pDoc,
-                  CPDF_Array* pArray,
-                  std::set<CPDF_Object*>* pVisited) override;
+                  const CPDF_Array* pArray,
+                  std::set<const CPDF_Object*>* pVisited) override;
   bool GetRGB(const float* pBuf, float* R, float* G, float* B) const override;
   void TranslateImageLine(uint8_t* pDestBuf,
                           const uint8_t* pSrcBuf,
diff --git a/core/fpdfapi/page/cpdf_docpagedata.cpp b/core/fpdfapi/page/cpdf_docpagedata.cpp
index 03db315912..9ac5c1e304 100644
--- a/core/fpdfapi/page/cpdf_docpagedata.cpp
+++ b/core/fpdfapi/page/cpdf_docpagedata.cpp
@@ -209,32 +209,33 @@ void CPDF_DocPageData::ReleaseFont(const CPDF_Dictionary* pFontDict) {
 }
 
 CPDF_ColorSpace* CPDF_DocPageData::GetColorSpace(
-    CPDF_Object* pCSObj,
+    const CPDF_Object* pCSObj,
     const CPDF_Dictionary* pResources) {
-  std::set<CPDF_Object*> visited;
+  std::set<const CPDF_Object*> visited;
   return GetColorSpaceGuarded(pCSObj, pResources, &visited);
 }
 
 CPDF_ColorSpace* CPDF_DocPageData::GetColorSpaceGuarded(
-    CPDF_Object* pCSObj,
+    const CPDF_Object* pCSObj,
     const CPDF_Dictionary* pResources,
-    std::set<CPDF_Object*>* pVisited) {
-  std::set<CPDF_Object*> visitedLocal;
+    std::set<const CPDF_Object*>* pVisited) {
+  std::set<const CPDF_Object*> visitedLocal;
   return GetColorSpaceInternal(pCSObj, pResources, pVisited, &visitedLocal);
 }
 
 CPDF_ColorSpace* CPDF_DocPageData::GetColorSpaceInternal(
-    CPDF_Object* pCSObj,
+    const CPDF_Object* pCSObj,
     const CPDF_Dictionary* pResources,
-    std::set<CPDF_Object*>* pVisited,
-    std::set<CPDF_Object*>* pVisitedInternal) {
+    std::set<const CPDF_Object*>* pVisited,
+    std::set<const CPDF_Object*>* pVisitedInternal) {
   if (!pCSObj)
     return nullptr;
 
   if (pdfium::ContainsKey(*pVisitedInternal, pCSObj))
     return nullptr;
 
-  pdfium::ScopedSetInsertion<CPDF_Object*> insertion(pVisitedInternal, pCSObj);
+  pdfium::ScopedSetInsertion<const CPDF_Object*> insertion(pVisitedInternal,
+                                                           pCSObj);
 
   if (pCSObj->IsName()) {
     ByteString name = pCSObj->GetString();
@@ -272,7 +273,7 @@ CPDF_ColorSpace* CPDF_DocPageData::GetColorSpaceInternal(
                                  pVisitedInternal);
   }
 
-  CPDF_Array* pArray = pCSObj->AsArray();
+  const CPDF_Array* pArray = pCSObj->AsArray();
   if (!pArray || pArray->IsEmpty())
     return nullptr;
 
@@ -304,7 +305,8 @@ CPDF_ColorSpace* CPDF_DocPageData::GetColorSpaceInternal(
   return csData->AddRef();
 }
 
-CPDF_ColorSpace* CPDF_DocPageData::GetCopiedColorSpace(CPDF_Object* pCSObj) {
+CPDF_ColorSpace* CPDF_DocPageData::GetCopiedColorSpace(
+    const CPDF_Object* pCSObj) {
   if (!pCSObj)
     return nullptr;
 
@@ -484,7 +486,7 @@ void CPDF_DocPageData::MaybePurgeFontFileStreamAcc(
 }
 
 CPDF_CountedColorSpace* CPDF_DocPageData::FindColorSpacePtr(
-    CPDF_Object* pCSObj) const {
+    const CPDF_Object* pCSObj) const {
   if (!pCSObj)
     return nullptr;
 
diff --git a/core/fpdfapi/page/cpdf_docpagedata.h b/core/fpdfapi/page/cpdf_docpagedata.h
index 5508f568be..2d22ee991d 100644
--- a/core/fpdfapi/page/cpdf_docpagedata.h
+++ b/core/fpdfapi/page/cpdf_docpagedata.h
@@ -40,17 +40,17 @@ class CPDF_DocPageData {
   void ReleaseFont(const CPDF_Dictionary* pFontDict);
 
   // Loads a colorspace.
-  CPDF_ColorSpace* GetColorSpace(CPDF_Object* pCSObj,
+  CPDF_ColorSpace* GetColorSpace(const CPDF_Object* pCSObj,
                                  const CPDF_Dictionary* pResources);
 
   // Loads a colorspace in a context that might be while loading another
   // colorspace. |pVisited| is passed recursively to avoid circular calls
   // involving CPDF_ColorSpace::Load().
-  CPDF_ColorSpace* GetColorSpaceGuarded(CPDF_Object* pCSObj,
+  CPDF_ColorSpace* GetColorSpaceGuarded(const CPDF_Object* pCSObj,
                                         const CPDF_Dictionary* pResources,
-                                        std::set<CPDF_Object*>* pVisited);
+                                        std::set<const CPDF_Object*>* pVisited);
 
-  CPDF_ColorSpace* GetCopiedColorSpace(CPDF_Object* pCSObj);
+  CPDF_ColorSpace* GetCopiedColorSpace(const CPDF_Object* pCSObj);
   void ReleaseColorSpace(const CPDF_Object* pColorSpace);
 
   CPDF_Pattern* GetPattern(CPDF_Object* pPatternObj,
@@ -67,7 +67,7 @@ class CPDF_DocPageData {
   RetainPtr<CPDF_StreamAcc> GetFontFileStreamAcc(CPDF_Stream* pFontStream);
   void MaybePurgeFontFileStreamAcc(const CPDF_Stream* pFontStream);
 
-  CPDF_CountedColorSpace* FindColorSpacePtr(CPDF_Object* pCSObj) const;
+  CPDF_CountedColorSpace* FindColorSpacePtr(const CPDF_Object* pCSObj) const;
   CPDF_CountedPattern* FindPatternPtr(CPDF_Object* pPatternObj) const;
 
  private:
@@ -79,10 +79,10 @@ class CPDF_DocPageData {
   // CPDF_ColorSpace::Load() and |pVisitedInternal| is also passed recursively
   // to avoid circular calls with this method calling itself.
   CPDF_ColorSpace* GetColorSpaceInternal(
-      CPDF_Object* pCSObj,
+      const CPDF_Object* pCSObj,
       const CPDF_Dictionary* pResources,
-      std::set<CPDF_Object*>* pVisited,
-      std::set<CPDF_Object*>* pVisitedInternal);
+      std::set<const CPDF_Object*>* pVisited,
+      std::set<const CPDF_Object*>* pVisitedInternal);
 
   bool m_bForceClear;
   UnownedPtr<CPDF_Document> const m_pPDFDoc;
diff --git a/core/fpdfapi/page/cpdf_expintfunc.cpp b/core/fpdfapi/page/cpdf_expintfunc.cpp
index 0b3dc24033..ac17b282a9 100644
--- a/core/fpdfapi/page/cpdf_expintfunc.cpp
+++ b/core/fpdfapi/page/cpdf_expintfunc.cpp
@@ -19,14 +19,14 @@ CPDF_ExpIntFunc::~CPDF_ExpIntFunc() {
   FX_Free(m_pEndValues);
 }
 
-bool CPDF_ExpIntFunc::v_Init(CPDF_Object* pObj,
-                             std::set<CPDF_Object*>* pVisited) {
-  CPDF_Dictionary* pDict = pObj->GetDict();
+bool CPDF_ExpIntFunc::v_Init(const CPDF_Object* pObj,
+                             std::set<const CPDF_Object*>* pVisited) {
+  const CPDF_Dictionary* pDict = pObj->GetDict();
   if (!pDict)
     return false;
 
   {
-    CPDF_Number* pExponent = ToNumber(pDict->GetObjectFor("N"));
+    const CPDF_Number* pExponent = ToNumber(pDict->GetObjectFor("N"));
     if (!pExponent)
       return false;
 
diff --git a/core/fpdfapi/page/cpdf_expintfunc.h b/core/fpdfapi/page/cpdf_expintfunc.h
index 3ff6a7eb22..9ea9f5ccb8 100644
--- a/core/fpdfapi/page/cpdf_expintfunc.h
+++ b/core/fpdfapi/page/cpdf_expintfunc.h
@@ -17,7 +17,8 @@ class CPDF_ExpIntFunc : public CPDF_Function {
   ~CPDF_ExpIntFunc() override;
 
   // CPDF_Function
-  bool v_Init(CPDF_Object* pObj, std::set<CPDF_Object*>* pVisited) override;
+  bool v_Init(const CPDF_Object* pObj,
+              std::set<const CPDF_Object*>* pVisited) override;
   bool v_Call(const float* inputs, float* results) const override;
 
   uint32_t m_nOrigOutputs = 0;
diff --git a/core/fpdfapi/page/cpdf_function.cpp b/core/fpdfapi/page/cpdf_function.cpp
index a43c887e71..ad3b666a1f 100644
--- a/core/fpdfapi/page/cpdf_function.cpp
+++ b/core/fpdfapi/page/cpdf_function.cpp
@@ -18,26 +18,27 @@
 #include "third_party/base/ptr_util.h"
 
 // static
-std::unique_ptr<CPDF_Function> CPDF_Function::Load(CPDF_Object* pFuncObj) {
-  std::set<CPDF_Object*> visited;
+std::unique_ptr<CPDF_Function> CPDF_Function::Load(
+    const CPDF_Object* pFuncObj) {
+  std::set<const CPDF_Object*> visited;
   return Load(pFuncObj, &visited);
 }
 
 // static
 std::unique_ptr<CPDF_Function> CPDF_Function::Load(
-    CPDF_Object* pFuncObj,
-    std::set<CPDF_Object*>* pVisited) {
+    const CPDF_Object* pFuncObj,
+    std::set<const CPDF_Object*>* pVisited) {
   if (!pFuncObj)
     return nullptr;
 
   if (pdfium::ContainsKey(*pVisited, pFuncObj))
     return nullptr;
-  pdfium::ScopedSetInsertion<CPDF_Object*> insertion(pVisited, pFuncObj);
+  pdfium::ScopedSetInsertion<const CPDF_Object*> insertion(pVisited, pFuncObj);
 
   int iType = -1;
-  if (CPDF_Stream* pStream = pFuncObj->AsStream())
+  if (const CPDF_Stream* pStream = pFuncObj->AsStream())
     iType = pStream->GetDict()->GetIntegerFor("FunctionType");
-  else if (CPDF_Dictionary* pDict = pFuncObj->AsDictionary())
+  else if (const CPDF_Dictionary* pDict = pFuncObj->AsDictionary())
     iType = pDict->GetIntegerFor("FunctionType");
 
   std::unique_ptr<CPDF_Function> pFunc;
@@ -78,11 +79,13 @@ CPDF_Function::~CPDF_Function() {
   FX_Free(m_pRanges);
 }
 
-bool CPDF_Function::Init(CPDF_Object* pObj, std::set<CPDF_Object*>* pVisited) {
-  CPDF_Stream* pStream = pObj->AsStream();
-  CPDF_Dictionary* pDict = pStream ? pStream->GetDict() : pObj->AsDictionary();
+bool CPDF_Function::Init(const CPDF_Object* pObj,
+                         std::set<const CPDF_Object*>* pVisited) {
+  const CPDF_Stream* pStream = pObj->AsStream();
+  const CPDF_Dictionary* pDict =
+      pStream ? pStream->GetDict() : pObj->AsDictionary();
 
-  CPDF_Array* pDomains = pDict->GetArrayFor("Domain");
+  const CPDF_Array* pDomains = pDict->GetArrayFor("Domain");
   if (!pDomains)
     return false;
 
diff --git a/core/fpdfapi/page/cpdf_function.h b/core/fpdfapi/page/cpdf_function.h
index 82a3a54327..c2f2a4bb4e 100644
--- a/core/fpdfapi/page/cpdf_function.h
+++ b/core/fpdfapi/page/cpdf_function.h
@@ -25,7 +25,7 @@ class CPDF_Function {
     kType4PostScript = 4,
   };
 
-  static std::unique_ptr<CPDF_Function> Load(CPDF_Object* pFuncObj);
+  static std::unique_ptr<CPDF_Function> Load(const CPDF_Object* pFuncObj);
   static Type IntegerToFunctionType(int iType);
 
   virtual ~CPDF_Function();
@@ -51,10 +51,12 @@ class CPDF_Function {
  protected:
   explicit CPDF_Function(Type type);
 
-  static std::unique_ptr<CPDF_Function> Load(CPDF_Object* pFuncObj,
-                                             std::set<CPDF_Object*>* pVisited);
-  bool Init(CPDF_Object* pObj, std::set<CPDF_Object*>* pVisited);
-  virtual bool v_Init(CPDF_Object* pObj, std::set<CPDF_Object*>* pVisited) = 0;
+  static std::unique_ptr<CPDF_Function> Load(
+      const CPDF_Object* pFuncObj,
+      std::set<const CPDF_Object*>* pVisited);
+  bool Init(const CPDF_Object* pObj, std::set<const CPDF_Object*>* pVisited);
+  virtual bool v_Init(const CPDF_Object* pObj,
+                      std::set<const CPDF_Object*>* pVisited) = 0;
   virtual bool v_Call(const float* inputs, float* results) const = 0;
 
   uint32_t m_nInputs;
diff --git a/core/fpdfapi/page/cpdf_image.cpp b/core/fpdfapi/page/cpdf_image.cpp
index 9ce4268a36..8720342d35 100644
--- a/core/fpdfapi/page/cpdf_image.cpp
+++ b/core/fpdfapi/page/cpdf_image.cpp
@@ -353,7 +353,7 @@ RetainPtr<CFX_DIBSource> CPDF_Image::DetachMask() {
   return std::move(m_pMask);
 }
 
-bool CPDF_Image::StartLoadDIBSource(CPDF_Dictionary* pFormResource,
+bool CPDF_Image::StartLoadDIBSource(const CPDF_Dictionary* pFormResource,
                                     CPDF_Dictionary* pPageResource,
                                     bool bStdCS,
                                     uint32_t GroupFamily,
diff --git a/core/fpdfapi/page/cpdf_image.h b/core/fpdfapi/page/cpdf_image.h
index 73ea92c666..9281a2c77d 100644
--- a/core/fpdfapi/page/cpdf_image.h
+++ b/core/fpdfapi/page/cpdf_image.h
@@ -50,7 +50,7 @@ class CPDF_Image : public Retainable {
   void ResetCache(CPDF_Page* pPage, const RetainPtr<CFX_DIBitmap>& pDIBitmap);
 
   // Returns whether to Continue() or not.
-  bool StartLoadDIBSource(CPDF_Dictionary* pFormResource,
+  bool StartLoadDIBSource(const CPDF_Dictionary* pFormResource,
                           CPDF_Dictionary* pPageResource,
                           bool bStdCS = false,
                           uint32_t GroupFamily = 0,
diff --git a/core/fpdfapi/page/cpdf_meshstream.cpp b/core/fpdfapi/page/cpdf_meshstream.cpp
index 579678af41..57a5dd1da1 100644
--- a/core/fpdfapi/page/cpdf_meshstream.cpp
+++ b/core/fpdfapi/page/cpdf_meshstream.cpp
@@ -93,8 +93,8 @@ CPDF_MeshVertex::~CPDF_MeshVertex() = default;
 CPDF_MeshStream::CPDF_MeshStream(
     ShadingType type,
     const std::vector<std::unique_ptr<CPDF_Function>>& funcs,
-    CPDF_Stream* pShadingStream,
-    CPDF_ColorSpace* pCS)
+    const CPDF_Stream* pShadingStream,
+    const CPDF_ColorSpace* pCS)
     : m_type(type),
       m_funcs(funcs),
       m_pShadingStream(pShadingStream),
@@ -120,7 +120,7 @@ bool CPDF_MeshStream::Load() {
   m_pStream->LoadAllDataFiltered();
   m_BitStream = pdfium::MakeUnique<CFX_BitStream>(
       pdfium::make_span(m_pStream->GetData(), m_pStream->GetSize()));
-  CPDF_Dictionary* pDict = m_pShadingStream->GetDict();
+  const CPDF_Dictionary* pDict = m_pShadingStream->GetDict();
   m_nCoordBits = pDict->GetIntegerFor("BitsPerCoordinate");
   m_nComponentBits = pDict->GetIntegerFor("BitsPerComponent");
   if (ShouldCheckBPC(m_type)) {
@@ -139,7 +139,7 @@ bool CPDF_MeshStream::Load() {
     return false;
 
   m_nComponents = m_funcs.empty() ? nComponents : 1;
-  CPDF_Array* pDecode = pDict->GetArrayFor("Decode");
+  const CPDF_Array* pDecode = pDict->GetArrayFor("Decode");
   if (!pDecode || pDecode->GetCount() != 4 + m_nComponents * 2)
     return false;
 
diff --git a/core/fpdfapi/page/cpdf_meshstream.h b/core/fpdfapi/page/cpdf_meshstream.h
index 9c97e09c15..1148494578 100644
--- a/core/fpdfapi/page/cpdf_meshstream.h
+++ b/core/fpdfapi/page/cpdf_meshstream.h
@@ -37,8 +37,8 @@ class CPDF_MeshStream {
  public:
   CPDF_MeshStream(ShadingType type,
                   const std::vector<std::unique_ptr<CPDF_Function>>& funcs,
-                  CPDF_Stream* pShadingStream,
-                  CPDF_ColorSpace* pCS);
+                  const CPDF_Stream* pShadingStream,
+                  const CPDF_ColorSpace* pCS);
   ~CPDF_MeshStream();
 
   bool Load();
@@ -66,8 +66,8 @@ class CPDF_MeshStream {
 
   const ShadingType m_type;
   const std::vector<std::unique_ptr<CPDF_Function>>& m_funcs;
-  UnownedPtr<CPDF_Stream> const m_pShadingStream;
-  UnownedPtr<CPDF_ColorSpace> const m_pCS;
+  UnownedPtr<const CPDF_Stream> const m_pShadingStream;
+  UnownedPtr<const CPDF_ColorSpace> const m_pCS;
   uint32_t m_nCoordBits;
   uint32_t m_nComponentBits;
   uint32_t m_nFlagBits;
diff --git a/core/fpdfapi/page/cpdf_pageobjectholder.h b/core/fpdfapi/page/cpdf_pageobjectholder.h
index 47c02fcf44..dc1a607cf0 100644
--- a/core/fpdfapi/page/cpdf_pageobjectholder.h
+++ b/core/fpdfapi/page/cpdf_pageobjectholder.h
@@ -86,6 +86,7 @@ class CPDF_PageObjectHolder {
   void Transform(const CFX_Matrix& matrix);
   CFX_FloatRect CalcBoundingBox() const;
 
+  // TODO(thestig): Move |m_pFormStream| into CPDF_Form.
   UnownedPtr<CPDF_Stream> m_pFormStream;
   UnownedPtr<CPDF_Dictionary> m_pPageResources;
   UnownedPtr<CPDF_Dictionary> m_pResources;
diff --git a/core/fpdfapi/page/cpdf_patterncs.cpp b/core/fpdfapi/page/cpdf_patterncs.cpp
index 37e91aa4e0..69be3d2b82 100644
--- a/core/fpdfapi/page/cpdf_patterncs.cpp
+++ b/core/fpdfapi/page/cpdf_patterncs.cpp
@@ -16,7 +16,8 @@ CPDF_PatternCS::CPDF_PatternCS(CPDF_Document* pDoc)
       m_pCountedBaseCS(nullptr) {}
 
 CPDF_PatternCS::~CPDF_PatternCS() {
-  CPDF_ColorSpace* pCS = m_pCountedBaseCS ? m_pCountedBaseCS->get() : nullptr;
+  const CPDF_ColorSpace* pCS =
+      m_pCountedBaseCS ? m_pCountedBaseCS->get() : nullptr;
   if (pCS && m_pDocument) {
     auto* pPageData = m_pDocument->GetPageData();
     if (pPageData)
@@ -29,9 +30,9 @@ void CPDF_PatternCS::InitializeStockPattern() {
 }
 
 uint32_t CPDF_PatternCS::v_Load(CPDF_Document* pDoc,
-                                CPDF_Array* pArray,
-                                std::set<CPDF_Object*>* pVisited) {
-  CPDF_Object* pBaseCS = pArray->GetDirectObjectAt(1);
+                                const CPDF_Array* pArray,
+                                std::set<const CPDF_Object*>* pVisited) {
+  const CPDF_Object* pBaseCS = pArray->GetDirectObjectAt(1);
   if (pBaseCS == m_pArray)
     return 0;
 
diff --git a/core/fpdfapi/page/cpdf_patterncs.h b/core/fpdfapi/page/cpdf_patterncs.h
index 45365cc738..23735fd8f2 100644
--- a/core/fpdfapi/page/cpdf_patterncs.h
+++ b/core/fpdfapi/page/cpdf_patterncs.h
@@ -24,8 +24,8 @@ class CPDF_PatternCS : public CPDF_ColorSpace {
 
   // CPDF_ColorSpace:
   uint32_t v_Load(CPDF_Document* pDoc,
-                  CPDF_Array* pArray,
-                  std::set<CPDF_Object*>* pVisited) override;
+                  const CPDF_Array* pArray,
+                  std::set<const CPDF_Object*>* pVisited) override;
   bool GetRGB(const float* pBuf, float* R, float* G, float* B) const override;
   CPDF_PatternCS* AsPatternCS() override;
   const CPDF_PatternCS* AsPatternCS() const override;
@@ -35,8 +35,8 @@ class CPDF_PatternCS : public CPDF_ColorSpace {
                      float* B) const override;
 
  private:
-  CPDF_ColorSpace* m_pBaseCS;
-  CPDF_CountedColorSpace* m_pCountedBaseCS;
+  const CPDF_ColorSpace* m_pBaseCS;
+  const CPDF_CountedColorSpace* m_pCountedBaseCS;
 };
 
 #endif  // CORE_FPDFAPI_PAGE_CPDF_PATTERNCS_H_
diff --git a/core/fpdfapi/page/cpdf_psfunc.cpp b/core/fpdfapi/page/cpdf_psfunc.cpp
index 2230d4e241..be0afe9659 100644
--- a/core/fpdfapi/page/cpdf_psfunc.cpp
+++ b/core/fpdfapi/page/cpdf_psfunc.cpp
@@ -13,7 +13,8 @@ CPDF_PSFunc::CPDF_PSFunc() : CPDF_Function(Type::kType4PostScript) {}
 
 CPDF_PSFunc::~CPDF_PSFunc() {}
 
-bool CPDF_PSFunc::v_Init(CPDF_Object* pObj, std::set<CPDF_Object*>* pVisited) {
+bool CPDF_PSFunc::v_Init(const CPDF_Object* pObj,
+                         std::set<const CPDF_Object*>* pVisited) {
   auto pAcc = pdfium::MakeRetain<CPDF_StreamAcc>(pObj->AsStream());
   pAcc->LoadAllDataFiltered();
   return m_PS.Parse(pAcc->GetSpan());
diff --git a/core/fpdfapi/page/cpdf_psfunc.h b/core/fpdfapi/page/cpdf_psfunc.h
index b4bc5bd2ef..459da5a599 100644
--- a/core/fpdfapi/page/cpdf_psfunc.h
+++ b/core/fpdfapi/page/cpdf_psfunc.h
@@ -20,7 +20,8 @@ class CPDF_PSFunc : public CPDF_Function {
   ~CPDF_PSFunc() override;
 
   // CPDF_Function
-  bool v_Init(CPDF_Object* pObj, std::set<CPDF_Object*>* pVisited) override;
+  bool v_Init(const CPDF_Object* pObj,
+              std::set<const CPDF_Object*>* pVisited) override;
   bool v_Call(const float* inputs, float* results) const override;
 
  private:
diff --git a/core/fpdfapi/page/cpdf_sampledfunc.cpp b/core/fpdfapi/page/cpdf_sampledfunc.cpp
index 3777254f34..9f19c1c468 100644
--- a/core/fpdfapi/page/cpdf_sampledfunc.cpp
+++ b/core/fpdfapi/page/cpdf_sampledfunc.cpp
@@ -36,9 +36,9 @@ CPDF_SampledFunc::CPDF_SampledFunc() : CPDF_Function(Type::kType0Sampled) {}
 
 CPDF_SampledFunc::~CPDF_SampledFunc() {}
 
-bool CPDF_SampledFunc::v_Init(CPDF_Object* pObj,
-                              std::set<CPDF_Object*>* pVisited) {
-  CPDF_Stream* pStream = pObj->AsStream();
+bool CPDF_SampledFunc::v_Init(const CPDF_Object* pObj,
+                              std::set<const CPDF_Object*>* pVisited) {
+  const CPDF_Stream* pStream = pObj->AsStream();
   if (!pStream)
     return false;
 
diff --git a/core/fpdfapi/page/cpdf_sampledfunc.h b/core/fpdfapi/page/cpdf_sampledfunc.h
index cbf2dd3648..bd129662cf 100644
--- a/core/fpdfapi/page/cpdf_sampledfunc.h
+++ b/core/fpdfapi/page/cpdf_sampledfunc.h
@@ -31,7 +31,8 @@ class CPDF_SampledFunc : public CPDF_Function {
   ~CPDF_SampledFunc() override;
 
   // CPDF_Function
-  bool v_Init(CPDF_Object* pObj, std::set<CPDF_Object*>* pVisited) override;
+  bool v_Init(const CPDF_Object* pObj,
+              std::set<const CPDF_Object*>* pVisited) override;
   bool v_Call(const float* inputs, float* results) const override;
 
   const std::vector<SampleEncodeInfo>& GetEncodeInfo() const {
diff --git a/core/fpdfapi/page/cpdf_shadingpattern.cpp b/core/fpdfapi/page/cpdf_shadingpattern.cpp
index f1e75b726a..628155c575 100644
--- a/core/fpdfapi/page/cpdf_shadingpattern.cpp
+++ b/core/fpdfapi/page/cpdf_shadingpattern.cpp
@@ -83,7 +83,7 @@ bool CPDF_ShadingPattern::Load() {
       m_pFunctions.push_back(CPDF_Function::Load(pFunc));
     }
   }
-  CPDF_Object* pCSObj = pShadingDict->GetDirectObjectFor("ColorSpace");
+  const CPDF_Object* pCSObj = pShadingDict->GetDirectObjectFor("ColorSpace");
   if (!pCSObj)
     return false;
 
diff --git a/core/fpdfapi/page/cpdf_stitchfunc.cpp b/core/fpdfapi/page/cpdf_stitchfunc.cpp
index aed17828d9..2083a91623 100644
--- a/core/fpdfapi/page/cpdf_stitchfunc.cpp
+++ b/core/fpdfapi/page/cpdf_stitchfunc.cpp
@@ -22,8 +22,8 @@ CPDF_StitchFunc::CPDF_StitchFunc() : CPDF_Function(Type::kType3Stitching) {}
 
 CPDF_StitchFunc::~CPDF_StitchFunc() {}
 
-bool CPDF_StitchFunc::v_Init(CPDF_Object* pObj,
-                             std::set<CPDF_Object*>* pVisited) {
+bool CPDF_StitchFunc::v_Init(const CPDF_Object* pObj,
+                             std::set<const CPDF_Object*>* pVisited) {
   if (m_nInputs != kRequiredNumInputs)
     return false;
 
@@ -66,7 +66,7 @@ bool CPDF_StitchFunc::v_Init(CPDF_Object* pObj,
   {
     Optional<uint32_t> nOutputs;
     for (uint32_t i = 0; i < nSubs; ++i) {
-      CPDF_Object* pSub = pFunctionsArray->GetDirectObjectAt(i);
+      const CPDF_Object* pSub = pFunctionsArray->GetDirectObjectAt(i);
       if (pSub == pObj)
         return false;
 
diff --git a/core/fpdfapi/page/cpdf_stitchfunc.h b/core/fpdfapi/page/cpdf_stitchfunc.h
index d6dd63d2d5..20dac6cbc1 100644
--- a/core/fpdfapi/page/cpdf_stitchfunc.h
+++ b/core/fpdfapi/page/cpdf_stitchfunc.h
@@ -19,7 +19,8 @@ class CPDF_StitchFunc : public CPDF_Function {
   ~CPDF_StitchFunc() override;
 
   // CPDF_Function
-  bool v_Init(CPDF_Object* pObj, std::set<CPDF_Object*>* pVisited) override;
+  bool v_Init(const CPDF_Object* pObj,
+              std::set<const CPDF_Object*>* pVisited) override;
   bool v_Call(const float* inputs, float* results) const override;
 
   const std::vector<std::unique_ptr<CPDF_Function>>& GetSubFunctions() const {
diff --git a/core/fpdfapi/page/cpdf_streamcontentparser.cpp b/core/fpdfapi/page/cpdf_streamcontentparser.cpp
index 736e91b3c8..df69aa43b9 100644
--- a/core/fpdfapi/page/cpdf_streamcontentparser.cpp
+++ b/core/fpdfapi/page/cpdf_streamcontentparser.cpp
@@ -1161,7 +1161,7 @@ CPDF_ColorSpace* CPDF_StreamContentParser::FindColorSpace(
   if (name == "DeviceGray" || name == "DeviceCMYK" || name == "DeviceRGB") {
     ByteString defname = "Default";
     defname += name.Right(name.GetLength() - 7);
-    CPDF_Object* pDefObj = FindResourceObj("ColorSpace", defname);
+    const CPDF_Object* pDefObj = FindResourceObj("ColorSpace", defname);
     if (!pDefObj) {
       if (name == "DeviceGray") {
         return CPDF_ColorSpace::GetStockCS(PDFCS_DEVICEGRAY);
@@ -1173,7 +1173,7 @@ CPDF_ColorSpace* CPDF_StreamContentParser::FindColorSpace(
     }
     return m_pDocument->LoadColorSpace(pDefObj);
   }
-  CPDF_Object* pCSObj = FindResourceObj("ColorSpace", name);
+  const CPDF_Object* pCSObj = FindResourceObj("ColorSpace", name);
   if (!pCSObj) {
     m_bResourceMissing = true;
     return nullptr;
diff --git a/core/fpdfapi/page/cpdf_streamparser.cpp b/core/fpdfapi/page/cpdf_streamparser.cpp
index b6658ee5fb..8652490a22 100644
--- a/core/fpdfapi/page/cpdf_streamparser.cpp
+++ b/core/fpdfapi/page/cpdf_streamparser.cpp
@@ -114,7 +114,7 @@ CPDF_StreamParser::~CPDF_StreamParser() {}
 std::unique_ptr<CPDF_Stream> CPDF_StreamParser::ReadInlineStream(
     CPDF_Document* pDoc,
     std::unique_ptr<CPDF_Dictionary> pDict,
-    CPDF_Object* pCSObj) {
+    const CPDF_Object* pCSObj) {
   if (m_Pos < m_pBuf.size() && PDFCharIsWhitespace(m_pBuf[m_Pos]))
     m_Pos++;
 
diff --git a/core/fpdfapi/page/cpdf_streamparser.h b/core/fpdfapi/page/cpdf_streamparser.h
index 78727da481..062527813c 100644
--- a/core/fpdfapi/page/cpdf_streamparser.h
+++ b/core/fpdfapi/page/cpdf_streamparser.h
@@ -40,7 +40,7 @@ class CPDF_StreamParser {
   std::unique_ptr<CPDF_Stream> ReadInlineStream(
       CPDF_Document* pDoc,
       std::unique_ptr<CPDF_Dictionary> pDict,
-      CPDF_Object* pCSObj);
+      const CPDF_Object* pCSObj);
 
  private:
   friend class cpdf_streamparser_ReadHexString_Test;