Tunnel the CDD from the Print Preview javascript to the privet operation

printing/print_job_constants.cc

Index: printing/print_job_constants.cc
diff --git a/printing/print_job_constants.cc b/printing/print_job_constants.cc
index 9a28ddb132570277b05abcb15d92b5f4cd67ffd0..6ccc4c119e291365af5a454e1728073c66e9f146 100644
--- a/printing/print_job_constants.cc
+++ b/printing/print_job_constants.cc
@@ -15,6 +15,9 @@ const char kPreviewRequestID[] = "requestID";
 // Unique ID to identify a print preview UI.
 const char kPreviewUIID[] = "previewUIID";
 
+// Capabilities option. Contains the capabilities in CDD format.
+const char kSettingCapabilities[] = "capabilities";
+
 // Print using cloud print: true if selected, false if not.
 const char kSettingCloudPrintId[] = "cloudPrintID";