Add policy for blocking GCP printing.

chrome/common/pref_names.cc

Index: chrome/common/pref_names.cc
diff --git a/chrome/common/pref_names.cc b/chrome/common/pref_names.cc
index e65225aca27fd1cfd1b4587fd40a2d691de1b9a7..58bc373d369859724a541e83623ff1c520faaa7d 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -1553,6 +1553,9 @@ const char kCloudPrintRobotRefreshToken[] = "cloud_print.robot_refresh_token";
 const char kCloudPrintRobotEmail[] = "cloud_print.robot_email";
 // Indicates whether the Mac Virtual driver is enabled.
 const char kVirtualPrinterDriverEnabled[] = "cloud_print.enable_virtual_driver";
+// A boolean indicating whether submitting jobs to Google Cloud Print is
+// blocked by policy.
+const char kCloudPrintSubmitEnabled[] = "cloud_print.submit_enabled";
 
 // Preference to store proxy settings.
 const char kProxy[] = "proxy";