Fix draw order of popup annotations.

Bug: chromium:765375
Change-Id: Ifdbd33ca92ec7105778788f891095eaf280c18cf
Reviewed-on: https://pdfium-review.googlesource.com/14370
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>
diff --git a/fpdfsdk/cpdfsdk_baannot.cpp b/fpdfsdk/cpdfsdk_baannot.cpp
index 711d228..c551fee 100644
--- a/fpdfsdk/cpdfsdk_baannot.cpp
+++ b/fpdfsdk/cpdfsdk_baannot.cpp
@@ -353,3 +353,10 @@
   if (CPDF_Annot* pAnnot = m_pAnnot->GetPopupAnnot())
     pAnnot->SetOpenState(bOpenState);
 }
+
+int CPDFSDK_BAAnnot::GetLayoutOrder() const {
+  if (m_pAnnot->GetSubtype() == CPDF_Annot::Subtype::POPUP)
+    return 1;
+
+  return CPDFSDK_Annot::GetLayoutOrder();
+}
diff --git a/fpdfsdk/cpdfsdk_baannot.h b/fpdfsdk/cpdfsdk_baannot.h
index 1d71585..c7300c4 100644
--- a/fpdfsdk/cpdfsdk_baannot.h
+++ b/fpdfsdk/cpdfsdk_baannot.h
@@ -92,6 +92,8 @@
 
   void SetOpenState(bool bState);
 
+  int GetLayoutOrder() const override;
+
  protected:
   CFX_UnownedPtr<CPDF_Annot> const m_pAnnot;
 };