Check whether the annotation content is empty using CFX_WideString.

core/fpdfdoc/cpdf_annotlist.cpp

Index: core/fpdfdoc/cpdf_annotlist.cpp
diff --git a/core/fpdfdoc/cpdf_annotlist.cpp b/core/fpdfdoc/cpdf_annotlist.cpp
index 631978175c5d8b5662fcc2fe7e1f96a89ce2b0fe..31c8542daaf34f8fc9639694f4be3572762a3616 100644
--- a/core/fpdfdoc/cpdf_annotlist.cpp
+++ b/core/fpdfdoc/cpdf_annotlist.cpp
@@ -24,7 +24,9 @@ std::unique_ptr<CPDF_Annot> CreatePopupAnnot(CPDF_Annot* pAnnot,
   if (!pParentDict)
     return std::unique_ptr<CPDF_Annot>();
 
-  CFX_ByteString sContents = pParentDict->GetStringBy("Contents");
+  // TODO(jaepark): We shouldn't strip BOM for some strings and not for others.
+  // See pdfium:593.
+  CFX_WideString sContents = pParentDict->GetUnicodeTextBy("Contents");
   if (sContents.IsEmpty())
     return std::unique_ptr<CPDF_Annot>();
 
@@ -32,7 +34,7 @@ std::unique_ptr<CPDF_Annot> CreatePopupAnnot(CPDF_Annot* pAnnot,
   pAnnotDict->SetAtName("Type", "Annot");
   pAnnotDict->SetAtName("Subtype", "Popup");
   pAnnotDict->SetAtString("T", pParentDict->GetStringBy("T"));
-  pAnnotDict->SetAtString("Contents", sContents);
+  pAnnotDict->SetAtString("Contents", sContents.UTF8Encode());
 
   CFX_FloatRect rect = pParentDict->GetRectBy("Rect");
   rect.Normalize();