Add unit test for CXFA_FileRead.

core/fpdfapi/parser/cpdf_stream.cpp

Index: core/fpdfapi/parser/cpdf_stream.cpp
diff --git a/core/fpdfapi/parser/cpdf_stream.cpp b/core/fpdfapi/parser/cpdf_stream.cpp
index e8ee0229409f0e81e8c299de4fe6c1e2440697f1..64261b14d3bc70ce908367df8128708b2f7385e4 100644
--- a/core/fpdfapi/parser/cpdf_stream.cpp
+++ b/core/fpdfapi/parser/cpdf_stream.cpp
@@ -113,6 +113,10 @@ bool CPDF_Stream::ReadRawData(FX_FILESIZE offset,
   return true;
 }
 
+bool CPDF_Stream::HasFilter() const {
+  return m_pDict && m_pDict->KeyExist("Filter");
+}
+
 CFX_WideString CPDF_Stream::GetUnicodeText() const {
   CPDF_StreamAcc stream;
   stream.LoadAllData(this, false);