Allow the PrinterDetector to be constructed with a delegated profile.

chrome/browser/chromeos/printer_detector/printer_detector_factory.h

Index: chrome/browser/chromeos/printer_detector/printer_detector_factory.h
diff --git a/chrome/browser/chromeos/printer_detector/printer_detector_factory.h b/chrome/browser/chromeos/printer_detector/printer_detector_factory.h
index 252cba9d11a971cfb7f0eaf3144ef434cb554481..39e69d2c14f0f7991f4406f0158dc07251dd6dd7 100644
--- a/chrome/browser/chromeos/printer_detector/printer_detector_factory.h
+++ b/chrome/browser/chromeos/printer_detector/printer_detector_factory.h
@@ -24,11 +24,17 @@ class PrinterDetectorFactory : public BrowserContextKeyedServiceFactory {
 
   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;