Use more unique_ptrs in CPDF_Image.

core/fpdfapi/page/cpdf_imageobject.cpp

Index: core/fpdfapi/page/cpdf_imageobject.cpp
diff --git a/core/fpdfapi/page/cpdf_imageobject.cpp b/core/fpdfapi/page/cpdf_imageobject.cpp
index 2893c525b14d265aebe333328434762a0b1ff045..bb9182054810dde3cf6cea3eddb16f30d96845d5 100644
--- a/core/fpdfapi/page/cpdf_imageobject.cpp
+++ b/core/fpdfapi/page/cpdf_imageobject.cpp
@@ -19,15 +19,6 @@ CPDF_ImageObject::~CPDF_ImageObject() {
   Release();
 }
 
-CPDF_ImageObject* CPDF_ImageObject::Clone() const {
-  CPDF_ImageObject* obj = new CPDF_ImageObject;
-  obj->CopyData(this);
-
-  obj->m_pImage = m_pImage->Clone();
-  obj->m_Matrix = m_Matrix;
-  return obj;
-}
-
 CPDF_PageObject::Type CPDF_ImageObject::GetType() const {
   return IMAGE;
 }