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

ios/chrome/browser/safe_browsing/safe_browsing_service.h

Index: ios/chrome/browser/safe_browsing/safe_browsing_service.h
diff --git a/ios/chrome/browser/safe_browsing/safe_browsing_service.h b/ios/chrome/browser/safe_browsing/safe_browsing_service.h
index 4b3507a37c797c685a54623369691b60afafd611..f3649ba49bf7c129b540bfa1e987bf701aa6818d 100644
--- a/ios/chrome/browser/safe_browsing/safe_browsing_service.h
+++ b/ios/chrome/browser/safe_browsing/safe_browsing_service.h
@@ -9,6 +9,7 @@
 #define IOS_CHROME_BROWSER_SAFE_BROWSING_SAFE_BROWSING_SERVICE_H_
 
 #include <map>
+#include <memory>
 #include <string>
 
 #include "base/callback.h"
@@ -16,7 +17,6 @@
 #include "base/files/file_path.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
-#include "base/memory/scoped_ptr.h"
 #include "base/observer_list.h"
 #include "base/sequenced_task_runner_helpers.h"
 #include "ios/chrome/browser/safe_browsing/util.h"
@@ -108,7 +108,7 @@ class SafeBrowsingService
   // Adds a listener for when SafeBrowsing preferences might have changed.
   // To get the current state, the callback should call enabled_by_prefs().
   // Should only be called on the UI thread.
-  scoped_ptr<StateSubscription> RegisterStateCallback(
+  std::unique_ptr<StateSubscription> RegisterStateCallback(
       const base::Callback<void(void)>& callback);
 
   // Sends serialized download recovery report to backend.