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

ios/chrome/browser/bookmarks/bookmark_model_factory.h

Index: ios/chrome/browser/bookmarks/bookmark_model_factory.h
diff --git a/ios/chrome/browser/bookmarks/bookmark_model_factory.h b/ios/chrome/browser/bookmarks/bookmark_model_factory.h
index fceae9809b7a18a487e9cff409c07932732be179..a1e21ecd03312405555edfc110d446a1a79e07ad 100644
--- a/ios/chrome/browser/bookmarks/bookmark_model_factory.h
+++ b/ios/chrome/browser/bookmarks/bookmark_model_factory.h
@@ -5,8 +5,9 @@
 #ifndef IOS_CHROME_BROWSER_BOOKMARKS_BOOKMARK_MODEL_FACTORY_H_
 #define IOS_CHROME_BROWSER_BOOKMARKS_BOOKMARK_MODEL_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 {
@@ -41,7 +42,7 @@ class BookmarkModelFactory : public BrowserStateKeyedServiceFactory {
   // BrowserStateKeyedServiceFactory implementation.
   void RegisterBrowserStatePrefs(
       user_prefs::PrefRegistrySyncable* registry) override;
-  scoped_ptr<KeyedService> BuildServiceInstanceFor(
+  std::unique_ptr<KeyedService> BuildServiceInstanceFor(
       web::BrowserState* context) const override;
   web::BrowserState* GetBrowserStateToUse(
       web::BrowserState* context) const override;