Enable Native CUPS printing on Chrome OS.

chrome/browser/chromeos/printer_detector/printer_detector_factory.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/chromeos/printer_detector/printer_detector_factory.h"
 
 #include "base/command_line.h"
 #include "chrome/browser/chromeos/printer_detector/printer_detector.h"
 #include "chrome/browser/chromeos/printing/printers_manager_factory.h"
 #include "chrome/browser/profiles/profile.h"
@@ skipping 27 matching lines @@
   DependsOn(
       extensions::ExtensionsBrowserClient::Get()->GetExtensionSystemFactory());
   DependsOn(PrintersManagerFactory::GetInstance());
 }
 
 PrinterDetectorFactory::~PrinterDetectorFactory() {
 }
 
 KeyedService* PrinterDetectorFactory::BuildServiceInstanceFor(
     content::BrowserContext* context) const {
-  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
-          ::switches::kEnableNativeCups)) {
+  if (!base::CommandLine::ForCurrentProcess()->HasSwitch(
+          ::switches::kDisableNativeCups)) {
     return PrinterDetector::CreateCups(Profile::FromBrowserContext(context))

[Carlson, 2017/03/31 21:45:52]

Probably slightly better to flip the contents of the if and else blocks here
instead of inverting the condition.  if (!disabled) is a quasi-double-negative.

[skau, 2017/03/31 23:29:09]

Done.

         .release();
   } else {
     return PrinterDetector::CreateLegacy(Profile::FromBrowserContext(context))
         .release();
   }
 }
 
 bool PrinterDetectorFactory::ServiceIsCreatedWithBrowserContext() const {
   return true;
 }
 
 bool PrinterDetectorFactory::ServiceIsNULLWhileTesting() const {
   return true;
 }
 
 }  // namespace chromeos