Use deferDeleteTempFile instead of DeleteOnClose

internal/driver/fetch.go

 		}
 		profileFile, openErr := os.Open(profileFilePath)
 		if openErr != nil {
-			os.Remove(profileFilePath)
 			return nil, openErr
 		}
-		return DeleteOnClose(profileFile), nil
+		return profileFile, nil
 	}
 	return sourceFile, nil
 }
 		return "", err
 	}
 	cmd := exec.Command("perf_to_profile", perfPath, profilePath)
+	// If perf_to_profile failed before generating the file, this defer
+	// is just a no-op.
+	deferDeleteTempFile(profilePath)
 	if err := cmd.Run(); err != nil {
-		os.Remove(profilePath)
 		return "", err
 	}
 	return profilePath, nil

internal/driver/tempfile.go

 	return os.Create(path)
 }
 
-type VolatileFile struct {
-	*os.File
-}
-
-func (file VolatileFile) Close() error {
-	if err := file.File.Close(); err != nil {
-		return err
-	}
-	if err := os.Remove(file.Name()); err != nil {
-		return err
-	}
-	return nil
-}
-
-// DeleteOnClose deletes file on Close().
-func DeleteOnClose(file *os.File) VolatileFile {
-	return VolatileFile {
-		File: file,
-	}
-}
-
 var tempFiles []string
 var tempFilesMu = sync.Mutex{}