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..989806b1afd7735690e8bbf2371c36abbf4dc2ed 100644
--- a/mojo/data_pipe_utils/data_pipe_utils.h
+++ b/mojo/data_pipe_utils/data_pipe_utils.h
@@ -42,11 +42,11 @@ bool BlockingCopyToString(ScopedDataPipeConsumerHandle source,
 bool BlockingCopyFromString(const std::string& source,
                             const ScopedDataPipeProducerHandle& destination);
 
-// Synchronously copies data from source to the destination file returning true
-// on success and false on error.  In case of an error, |destination| holds the
-// data that could be read from the source before the error occured.
-bool BlockingCopyToFile(ScopedDataPipeConsumerHandle source,
-                        const base::FilePath& destination);
+// Synchronously copies source data to a temporary file, returning a file
+// pointer on success and NULL on error. The temporary file is unlinked
+// immediately so that it is only accessible by file pointer (and removed once
+// closed or the creating process dies).
+FILE* BlockingCopyToTempFile(ScopedDataPipeConsumerHandle source);
 
 }  // namespace common
 }  // namespace mojo