Make chromeos CUPS printing code namespaces consistent.

chromeos/printing/printing_constants.h

Index: chromeos/printing/printing_constants.h
diff --git a/chromeos/printing/printing_constants.h b/chromeos/printing/printing_constants.h
index 65e32299a1a4fa018fc86582deefe44c38664414..1ea57164358e49cda858f54071382889128bdee8 100644
--- a/chromeos/printing/printing_constants.h
+++ b/chromeos/printing/printing_constants.h
@@ -6,14 +6,12 @@
 #define CHROMEOS_PRINTING_PRINTING_CONSTANTS_H_
 
 namespace chromeos {
-namespace printing {
 
 // Maximum size of a PPD file that we will accept, currently 250k.  This number
 // is relatively
 // arbitrary, we just don't want to try to handle ridiculously huge files.
 constexpr size_t kMaxPpdSizeBytes = 250 * 1024;
 
-}  // namespace printing
 }  // namespace chromeos
 
 #endif  // CHROMEOS_PRINTING_PRINTING_CONSTANTS_H_