Revert "Remove CFX_ByteTextBuf from cpdfsdk_interform.cpp and others."

This reverts commit aea80dcc0abc0c310316fa502f91a359bc684758.

Reason for revert: WriteBuf's behavior was altered

Original change's description:
> Remove CFX_ByteTextBuf from cpdfsdk_interform.cpp and others.
> 
> Bug: pdfium:731
> Change-Id: I61d38ab3f2b0ac68b8479ade25bab50f3a73c27b
> Reviewed-on: https://pdfium-review.googlesource.com/9770
> Reviewed-by: Tom Sepez <tsepez@chromium.org>
> Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>

TBR=tsepez@chromium.org,hnakashima@chromium.org,rharrison@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: pdfium:731
Change-Id: Ic66a2641c259173fb3792f7a4206e19ee4707fc9
Reviewed-on: https://pdfium-review.googlesource.com/10150
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>

1 files changed, 3 insertions, 6 deletions

diff --git a/core/fpdfapi/parser/cfdf_document.cpp b/core/fpdfapi/parser/cfdf_document.cpp
index b00806967b..85e2f6ef04 100644
--- a/core/fpdfapi/parser/cfdf_document.cpp
+++ b/core/fpdfapi/parser/cfdf_document.cpp
@@ -7,7 +7,6 @@
 #include "core/fpdfapi/parser/cfdf_document.h"
 
 #include <memory>
-#include <sstream>
 #include <utility>
 
 #include "core/fpdfapi/edit/cpdf_creator.h"
@@ -89,11 +88,10 @@ void CFDF_Document::ParseStream(
   }
 }
 
-CFX_ByteString CFDF_Document::WriteToString() const {
+bool CFDF_Document::WriteBuf(CFX_ByteTextBuf& buf) const {
   if (!m_pRootDict)
-    return CFX_ByteString();
+    return false;
 
-  std::ostringstream buf;
   buf << "%FDF-1.2\r\n";
   for (const auto& pair : *this)
     buf << pair.first << " 0 obj\r\n"
@@ -101,6 +99,5 @@ CFX_ByteString CFDF_Document::WriteToString() const {
 
   buf << "trailer\r\n<</Root " << m_pRootDict->GetObjNum()
       << " 0 R>>\r\n%%EOF\r\n";
-
-  return CFX_ByteString(buf);
+  return true;
 }