Make CPDF_Image() constructors saner.

core/fpdfapi/parser/cpdf_stream.h

Index: core/fpdfapi/parser/cpdf_stream.h
diff --git a/core/fpdfapi/parser/cpdf_stream.h b/core/fpdfapi/parser/cpdf_stream.h
index 575a9ebe0b2ac40c58e2a06a44bbe1f7a3dab185..756eccfba1cfbb0d8253604b2cbdbefc184b6eb5 100644
--- a/core/fpdfapi/parser/cpdf_stream.h
+++ b/core/fpdfapi/parser/cpdf_stream.h
@@ -58,7 +58,7 @@ class CPDF_Stream : public CPDF_Object {
   IFX_FileRead* m_pFile = nullptr;
 };
 
-using UniqueStream = std::unique_ptr<CPDF_Stream, ReleaseDeleter<CPDF_Stream>>;
+using UniqueStream = std::unique_ptr<CPDF_Stream, ReleaseDeleter<CPDF_Object>>;
 
 inline CPDF_Stream* ToStream(CPDF_Object* obj) {
   return obj ? obj->AsStream() : nullptr;
@@ -68,4 +68,12 @@ inline const CPDF_Stream* ToStream(const CPDF_Object* obj) {
   return obj ? obj->AsStream() : nullptr;
 }
 
+inline UniqueStream ToStream(UniqueObject obj) {
+  CPDF_Stream* pStream = ToStream(obj.get());
+  if (!pStream)
+    return nullptr;
+  obj.release();
+  return UniqueStream(pStream);
+}
+
 #endif  // CORE_FPDFAPI_PARSER_CPDF_STREAM_H_