Move fxcrt::{Byte,Wide}Strings with std::move().

Remove some string copies in barcode that were noticed whilst
looking for moves.

Change-Id: Ieda34d00f633576ba1f0dca283dcdabfb36f236c
Reviewed-on: https://pdfium-review.googlesource.com/35410
Reviewed-by: dsinclair <dsinclair@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>
diff --git a/fxbarcode/cbc_code39.cpp b/fxbarcode/cbc_code39.cpp
index 9715c25..52859e1 100644
--- a/fxbarcode/cbc_code39.cpp
+++ b/fxbarcode/cbc_code39.cpp
@@ -40,15 +40,12 @@
   int32_t outHeight = 0;
   auto* pWriter = GetOnedCode39Writer();
   WideString filtercontents = pWriter->FilterContents(contents);
-  WideString renderContents = pWriter->RenderTextContents(contents);
-  m_renderContents = renderContents;
+  m_renderContents = pWriter->RenderTextContents(contents);
   ByteString byteString = filtercontents.UTF8Encode();
   std::unique_ptr<uint8_t, FxFreeDeleter> data(
       pWriter->Encode(byteString, format, outWidth, outHeight));
-  if (!data)
-    return false;
-  return pWriter->RenderResult(renderContents.AsStringView(), data.get(),
-                               outWidth);
+  return data && pWriter->RenderResult(m_renderContents.AsStringView(),
+                                       data.get(), outWidth);
 }
 
 bool CBC_Code39::RenderDevice(CFX_RenderDevice* device,