Created a blocking copy to temporary file function.

mojo/data_pipe_utils/data_pipe_utils.h

Index: mojo/data_pipe_utils/data_pipe_utils.h
diff --git a/mojo/data_pipe_utils/data_pipe_utils.h b/mojo/data_pipe_utils/data_pipe_utils.h
index 289fe12a8eda1b566de9f3db2f1b887fb94d1b60..88965a344eb5b3a40f29c13cd24ac70ecd135c6d 100644
--- a/mojo/data_pipe_utils/data_pipe_utils.h
+++ b/mojo/data_pipe_utils/data_pipe_utils.h
@@ -48,6 +48,12 @@ bool BlockingCopyFromString(const std::string& source,
 bool BlockingCopyToFile(ScopedDataPipeConsumerHandle source,
                         const base::FilePath& destination);
 
+// Similar to BlockingCopyToFile, but copies source data to a temporary
+// file which is unlinked immediately so that it is only accessible by
+// file descriptor (and removed once closed or the creating process dies).
+bool BlockingCopyToTempFile(ScopedDataPipeConsumerHandle source,
+                            FILE** fpp);
+
 }  // namespace common
 }  // namespace mojo