CPDF_Document::LoadPattern() and friends always have a valid matrix.

core/fpdfapi/fpdf_page/fpdf_page_doc.cpp

Index: core/fpdfapi/fpdf_page/fpdf_page_doc.cpp
diff --git a/core/fpdfapi/fpdf_page/fpdf_page_doc.cpp b/core/fpdfapi/fpdf_page/fpdf_page_doc.cpp
index dfc21b47cbf85a00adba87f2f56d3c32a7f446dc..8287ea562db17075c7eca494bfd9e14ee3453bdd 100644
--- a/core/fpdfapi/fpdf_page/fpdf_page_doc.cpp
+++ b/core/fpdfapi/fpdf_page/fpdf_page_doc.cpp
@@ -316,7 +316,7 @@ void CPDF_DocPageData::ReleaseColorSpace(CPDF_Object* pColorSpace) {
 
 CPDF_Pattern* CPDF_DocPageData::GetPattern(CPDF_Object* pPatternObj,
                                            FX_BOOL bShading,
-                                           const CFX_Matrix* matrix) {
+                                           const CFX_Matrix& matrix) {
   if (!pPatternObj)
     return nullptr;