Use StringPiece in cups_helper.cc.

printing/backend/cups_helper.h

Index: printing/backend/cups_helper.h
diff --git a/printing/backend/cups_helper.h b/printing/backend/cups_helper.h
index 873f1ec2821253c2493c8c5016821193400d3791..fd7601dc975978edc57c384d6fe92425d77e83cc 100644
--- a/printing/backend/cups_helper.h
+++ b/printing/backend/cups_helper.h
@@ -7,8 +7,7 @@
 
 #include <cups/cups.h>
 
-#include <string>
-
+#include "base/strings/string_piece.h"
 #include "printing/printing_export.h"
 
 class GURL;
@@ -37,8 +36,8 @@ class PRINTING_EXPORT HttpConnectionCUPS {
 // Helper function to parse and convert PPD capabilitites to
 // semantic options.
 PRINTING_EXPORT bool ParsePpdCapabilities(
-    const std::string& printer_name,
-    const std::string& printer_capabilities,
+    base::StringPiece printer_name,
+    base::StringPiece printer_capabilities,
     PrinterSemanticCapsAndDefaults* printer_info);
 
 }  // namespace printing