handle antialiased rendering as premultiplied

core/fpdfapi/render/cpdf_renderstatus.cpp

Index: core/fpdfapi/render/cpdf_renderstatus.cpp
diff --git a/core/fpdfapi/render/cpdf_renderstatus.cpp b/core/fpdfapi/render/cpdf_renderstatus.cpp
index 7c389ef37c664a08bdfda7b3f468dbf37b280237..202e7e3bb76b768fb7afbbe535273615a5588ca8 100644
--- a/core/fpdfapi/render/cpdf_renderstatus.cpp
+++ b/core/fpdfapi/render/cpdf_renderstatus.cpp
@@ -893,6 +893,9 @@ std::unique_ptr<CFX_DIBitmap> DrawPatternBitmap(
   CPDF_RenderContext context(pDoc, pCache);
   context.AppendLayer(pPattern->form(), &mtPattern2Bitmap);
   context.Render(&bitmap_device, &options, nullptr);
+#if defined _SKIA_SUPPORT_PATHS_
+  pBitmap->UnPreMultiply();
+#endif
   return pBitmap;
 }
 
@@ -1136,9 +1139,6 @@ void CPDF_RenderStatus::ProcessObjectNoClip(CPDF_PageObject* pObj,
 #if defined _SKIA_SUPPORT_
   DebugVerifyDeviceIsPreMultiplied();
 #endif
-#if defined _SKIA_SUPPORT_PATHS_
-  UnPreMultiplyDevice();
-#endif
 }
 
 bool CPDF_RenderStatus::DrawObjWithBlend(CPDF_PageObject* pObj,
@@ -1547,6 +1547,9 @@ bool CPDF_RenderStatus::ProcessTransparency(CPDF_PageObject* pPageObj,
                            nullptr, nullptr, &m_Options, 0, m_bDropObjects,
                            pFormResource, true);
   bitmap_render.ProcessObjectNoClip(pPageObj, &new_matrix);
+#if defined _SKIA_SUPPORT_PATHS_
+  bitmap->UnPreMultiply();
+#endif
   m_bStopped = bitmap_render.m_bStopped;
   if (pSMaskDict) {
     CFX_Matrix smask_matrix = *pPageObj->m_GeneralState.GetSMaskMatrix();
@@ -1650,12 +1653,6 @@ void CPDF_RenderStatus::DebugVerifyDeviceIsPreMultiplied() const {
 }
 #endif
 
-#if defined _SKIA_SUPPORT_PATHS_
-void CPDF_RenderStatus::UnPreMultiplyDevice() {
-  m_pDevice->UnPreMultiplyDevice();
-}
-#endif
-
 bool CPDF_RenderStatus::ProcessText(CPDF_TextObject* textobj,
                                     const CFX_Matrix* pObj2Device,
                                     CFX_PathData* pClippingPath) {