Make down-conversion explicit from CFX_Widetring to CFX_WideStringC.

fpdfsdk/fsdk_baseform.cpp

Index: fpdfsdk/fsdk_baseform.cpp
diff --git a/fpdfsdk/fsdk_baseform.cpp b/fpdfsdk/fsdk_baseform.cpp
index d195d87fc10a936379a3a2cc0722973137a1fb1e..827b05a4d56ee644532172b1ebebd7455a950f3b 100644
--- a/fpdfsdk/fsdk_baseform.cpp
+++ b/fpdfsdk/fsdk_baseform.cpp
@@ -69,7 +69,7 @@ CXFA_FFWidget* CPDFSDK_Widget::GetMixXFAWidget() const {
         }
 
         if (!sName.IsEmpty())
-          m_hMixXFAWidget = pDocView->GetWidgetByName(sName);
+          m_hMixXFAWidget = pDocView->GetWidgetByName(sName.AsWideStringC());
       }
     }
     return m_hMixXFAWidget;
@@ -85,7 +85,7 @@ CXFA_FFWidget* CPDFSDK_Widget::GetGroupMixXFAWidget() {
     if (CXFA_FFDocView* pDocView = pDoc->GetXFADocView()) {
       CFX_WideString sName = GetName();
       if (!sName.IsEmpty())
-        return pDocView->GetWidgetByName(sName);
+        return pDocView->GetWidgetByName(sName.AsWideStringC());
     }
   }
 
@@ -2453,7 +2453,7 @@ FX_BOOL CPDFSDK_InterForm::ExportFieldsToFDFTextBuf(
     bool bIncludeOrExclude,
     CFX_ByteTextBuf& textBuf) {
   std::unique_ptr<CFDF_Document> pFDF(m_pInterForm->ExportToFDF(
-      m_pDocument->GetPath(), fields, bIncludeOrExclude));
+      m_pDocument->GetPath().AsWideStringC(), fields, bIncludeOrExclude));
   return pFDF ? pFDF->WriteBuf(textBuf) : FALSE;
 }
 
@@ -2491,7 +2491,8 @@ FX_BOOL CPDFSDK_InterForm::SubmitForm(const CFX_WideString& sDestination,
 
   CPDFDoc_Environment* pEnv = m_pDocument->GetEnv();
   CFX_WideString wsPDFFilePath = m_pDocument->GetPath();
-  CFDF_Document* pFDFDoc = m_pInterForm->ExportToFDF(wsPDFFilePath);
+  CFDF_Document* pFDFDoc =
+      m_pInterForm->ExportToFDF(wsPDFFilePath.AsWideStringC());
   if (!pFDFDoc)
     return FALSE;
 
@@ -2520,7 +2521,8 @@ FX_BOOL CPDFSDK_InterForm::SubmitForm(const CFX_WideString& sDestination,
 }
 
 FX_BOOL CPDFSDK_InterForm::ExportFormToFDFTextBuf(CFX_ByteTextBuf& textBuf) {
-  CFDF_Document* pFDF = m_pInterForm->ExportToFDF(m_pDocument->GetPath());
+  CFDF_Document* pFDF =
+      m_pInterForm->ExportToFDF(m_pDocument->GetPath().AsWideStringC());
   if (!pFDF)
     return FALSE;