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

ios/chrome/browser/signin/about_signin_internals_factory.h

Index: ios/chrome/browser/signin/about_signin_internals_factory.h
diff --git a/ios/chrome/browser/signin/about_signin_internals_factory.h b/ios/chrome/browser/signin/about_signin_internals_factory.h
index 70175e7695170c227156fdb8ea18be7fdb8d4848..45d70f78b0a9e9589dc8caf5a82a436e7dd90054 100644
--- a/ios/chrome/browser/signin/about_signin_internals_factory.h
+++ b/ios/chrome/browser/signin/about_signin_internals_factory.h
@@ -5,8 +5,9 @@
 #ifndef IOS_CHROME_BROWSER_SIGNIN_ABOUT_SIGNIN_INTERNALS_FACTORY_H_
 #define IOS_CHROME_BROWSER_SIGNIN_ABOUT_SIGNIN_INTERNALS_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 {
@@ -39,7 +40,7 @@ class AboutSigninInternalsFactory : public BrowserStateKeyedServiceFactory {
   ~AboutSigninInternalsFactory() override;
 
   // BrowserStateKeyedServiceFactory:
-  scoped_ptr<KeyedService> BuildServiceInstanceFor(
+  std::unique_ptr<KeyedService> BuildServiceInstanceFor(
       web::BrowserState* context) const override;
   void RegisterBrowserStatePrefs(
       user_prefs::PrefRegistrySyncable* registry) override;