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

ios/chrome/browser/signin/about_signin_internals_factory.cc

Index: ios/chrome/browser/signin/about_signin_internals_factory.cc
diff --git a/ios/chrome/browser/signin/about_signin_internals_factory.cc b/ios/chrome/browser/signin/about_signin_internals_factory.cc
index 33f66fd9d940c6782294aae29990bcc98848d8b6..09ea8d04dd194163449c80280d0025b02fb082ca 100644
--- a/ios/chrome/browser/signin/about_signin_internals_factory.cc
+++ b/ios/chrome/browser/signin/about_signin_internals_factory.cc
@@ -45,11 +45,12 @@ AboutSigninInternalsFactory* AboutSigninInternalsFactory::GetInstance() {
   return base::Singleton<AboutSigninInternalsFactory>::get();
 }
 
-scoped_ptr<KeyedService> AboutSigninInternalsFactory::BuildServiceInstanceFor(
+std::unique_ptr<KeyedService>
+AboutSigninInternalsFactory::BuildServiceInstanceFor(
     web::BrowserState* context) const {
   ios::ChromeBrowserState* chrome_browser_state =
       ios::ChromeBrowserState::FromBrowserState(context);
-  scoped_ptr<AboutSigninInternals> service(new AboutSigninInternals(
+  std::unique_ptr<AboutSigninInternals> service(new AboutSigninInternals(
       OAuth2TokenServiceFactory::GetForBrowserState(chrome_browser_state),
       AccountTrackerServiceFactory::GetForBrowserState(chrome_browser_state),
       SigninManagerFactory::GetForBrowserState(chrome_browser_state),