Convert //ios from scoped_ptr to std::unique_ptr.

ios/chrome/browser/signin/signin_error_controller_factory.h

Index: ios/chrome/browser/signin/signin_error_controller_factory.h
diff --git a/ios/chrome/browser/signin/signin_error_controller_factory.h b/ios/chrome/browser/signin/signin_error_controller_factory.h
index c0ae7191573ab0184006f70f165cb72571080590..75fd678f19314f85698a9b9af48457675602639c 100644
--- a/ios/chrome/browser/signin/signin_error_controller_factory.h
+++ b/ios/chrome/browser/signin/signin_error_controller_factory.h
@@ -5,8 +5,9 @@
 #ifndef IOS_CHROME_BROWSER_SIGNIN_SIGNIN_ERROR_CONTROLLER_FACTORY_H_
 #define IOS_CHROME_BROWSER_SIGNIN_SIGNIN_ERROR_CONTROLLER_FACTORY_H_
 
+#include <memory>
+
 #include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
 #include "components/keyed_service/ios/browser_state_keyed_service_factory.h"
 
 namespace base {
@@ -35,7 +36,7 @@ class SigninErrorControllerFactory : public BrowserStateKeyedServiceFactory {
   ~SigninErrorControllerFactory() override;
 
   // BrowserStateKeyedServiceFactory implementation.
-  scoped_ptr<KeyedService> BuildServiceInstanceFor(
+  std::unique_ptr<KeyedService> BuildServiceInstanceFor(
       web::BrowserState* context) const override;
 
   DISALLOW_COPY_AND_ASSIGN(SigninErrorControllerFactory);