Allow the PrinterDetector to be constructed with a delegated profile.

chrome/browser/chromeos/printer_detector/printer_detector_factory.h

 // 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.
 
 #ifndef CHROME_BROWSER_CHROMEOS_PRINTER_DETECTOR_PRINTER_DETECTOR_FACTORY_H_
 #define CHROME_BROWSER_CHROMEOS_PRINTER_DETECTOR_PRINTER_DETECTOR_FACTORY_H_
 
 #include "base/lazy_instance.h"
 #include "base/macros.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 #include "extensions/browser/extension_system_provider.h"
 
 namespace content {
 class BrowserContext;
 }
 
 namespace chromeos {
 
 class PrinterDetector;
 
 class PrinterDetectorFactory : public BrowserContextKeyedServiceFactory {
  public:
   static PrinterDetectorFactory* GetInstance();
 
   PrinterDetector* Get(content::BrowserContext* context);
 
+ protected:
+  // BrowserContextKeyedServiceFactory:
+  content::BrowserContext* GetBrowserContextToUse(
+      content::BrowserContext* context) const override;
+
  private:
   friend struct base::LazyInstanceTraitsBase<PrinterDetectorFactory>;
   PrinterDetectorFactory();
   ~PrinterDetectorFactory() override;
 
+  // BrowserContextKeyedServiceFactory:
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* browser_context) const override;
   bool ServiceIsCreatedWithBrowserContext() const override;
   bool ServiceIsNULLWhileTesting() const override;
 
   DISALLOW_COPY_AND_ASSIGN(PrinterDetectorFactory);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_PRINTER_DETECTOR_PRINTER_DETECTOR_FACTORY_H_