diff --git a/components/services/bat_ads/bat_ads_impl.cc b/components/services/bat_ads/bat_ads_impl.cc
index 24e8c232493..ba4c07810e5 100644
--- a/components/services/bat_ads/bat_ads_impl.cc
+++ b/components/services/bat_ads/bat_ads_impl.cc
@@ -45,20 +45,11 @@ BatAdsImpl::BatAdsImpl(
 BatAdsImpl::~BatAdsImpl() = default;
 
 void BatAdsImpl::Initialize(InitializeCallback callback) {
-  auto* holder =
-      new CallbackHolder<InitializeCallback>(AsWeakPtr(), std::move(callback));
-
-  ads_->Initialize(
-      std::bind(BatAdsImpl::OnInitialize, holder, std::placeholders::_1));
+  ads_->Initialize(std::move(callback));
 }
 
 void BatAdsImpl::Shutdown(ShutdownCallback callback) {
-  auto* holder =
-      new CallbackHolder<ShutdownCallback>(AsWeakPtr(), std::move(callback));
-
-  auto shutdown_callback =
-      std::bind(BatAdsImpl::OnShutdown, holder, std::placeholders::_1);
-  ads_->Shutdown(shutdown_callback);
+  ads_->Shutdown(std::move(callback));
 }
 
 void BatAdsImpl::OnLocaleDidChange(const std::string& locale) {
@@ -296,24 +287,6 @@ void BatAdsImpl::OnDidUpdateResourceComponent(const std::string& id) {
 
 ///////////////////////////////////////////////////////////////////////////////
 
-void BatAdsImpl::OnInitialize(CallbackHolder<InitializeCallback>* holder,
-                              const bool success) {
-  if (holder->is_valid()) {
-    std::move(holder->get()).Run(success);
-  }
-
-  delete holder;
-}
-
-void BatAdsImpl::OnShutdown(CallbackHolder<ShutdownCallback>* holder,
-                            const bool success) {
-  if (holder->is_valid()) {
-    std::move(holder->get()).Run(success);
-  }
-
-  delete holder;
-}
-
 // static
 void BatAdsImpl::OnMaybeServeNewTabPageAd(
     CallbackHolder<MaybeServeNewTabPageAdCallback>* holder,
diff --git a/components/services/bat_ads/bat_ads_impl.h b/components/services/bat_ads/bat_ads_impl.h
index 9c32370d94c..20442159aab 100644
--- a/components/services/bat_ads/bat_ads_impl.h
+++ b/components/services/bat_ads/bat_ads_impl.h
@@ -159,11 +159,6 @@ class BatAdsImpl : public mojom::BatAds,
     T callback_;
   };
 
-  static void OnInitialize(CallbackHolder<InitializeCallback>* holder,
-                           bool success);
-  static void OnShutdown(CallbackHolder<ShutdownCallback>* holder,
-                         bool success);
-
   static void OnMaybeServeInlineContentAd(
       CallbackHolder<MaybeServeInlineContentAdCallback>* holder,
       const std::string& dimensions,
diff --git a/ios/browser/api/ads/brave_ads.mm b/ios/browser/api/ads/brave_ads.mm
index d45c3fe371a..5e2092265eb 100644
--- a/ios/browser/api/ads/brave_ads.mm
+++ b/ios/browser/api/ads/brave_ads.mm
@@ -269,11 +269,11 @@ ads::mojom::DBCommandResponseInfoPtr RunDBTransactionOnTaskRunner(
 
   adsClient = new AdsClientIOS(self);
   ads = ads::Ads::CreateInstance(adsClient);
-  ads->Initialize(^(const bool success) {
+  ads->Initialize(base::BindOnce(^(const bool success) {
     [self periodicallyCheckForAdsResourceUpdates];
     [self registerAdsResources];
     completion(success);
-  });
+  }));
 }
 
 - (void)updateWalletInfo:(NSString*)paymentId base64Seed:(NSString*)base64Seed {
@@ -302,7 +302,7 @@ ads::mojom::DBCommandResponseInfoPtr RunDBTransactionOnTaskRunner(
 - (void)shutdown:(nullable void (^)())completion {
   if ([self isAdsServiceRunning]) {
     dispatch_group_notify(self.prefsWriteGroup, dispatch_get_main_queue(), ^{
-      self->ads->Shutdown(^(bool) {
+      self->ads->Shutdown(base::BindOnce(^(bool) {
         if (self->ads != nil) {
           delete self->ads;
         }
@@ -322,7 +322,7 @@ ads::mojom::DBCommandResponseInfoPtr RunDBTransactionOnTaskRunner(
         if (completion) {
           completion();
         }
-      });
+      }));
     });
   } else {
     if (completion) {
@@ -467,7 +467,7 @@ ads::mojom::DBCommandResponseInfoPtr RunDBTransactionOnTaskRunner(
     return;
   }
   ads->RemoveAllHistory(base::BindOnce(^(const bool success) {
-    completion(success ? YES : NO);
+    completion(success);
   }));
 }
 
@@ -668,7 +668,7 @@ ads::mojom::DBCommandResponseInfoPtr RunDBTransactionOnTaskRunner(
   }
   ads->PurgeOrphanedAdEventsForType(static_cast<ads::mojom::AdType>(adType),
                                     base::BindOnce(^(const bool success) {
-                                      completion(success ? YES : NO);
+                                      completion(success);
                                     }));
 }
 
diff --git a/vendor/bat-native-ads/include/bat/ads/ads_callback.h b/vendor/bat-native-ads/include/bat/ads/ads_callback.h
index 0380bfae4b2..f317a885050 100644
--- a/vendor/bat-native-ads/include/bat/ads/ads_callback.h
+++ b/vendor/bat-native-ads/include/bat/ads/ads_callback.h
@@ -18,8 +18,8 @@
 
 namespace ads {
 
-using InitializeCallback = std::function<void(const bool)>;
-using ShutdownCallback = std::function<void(const bool)>;
+using InitializeCallback = base::OnceCallback<void(const bool)>;
+using ShutdownCallback = base::OnceCallback<void(const bool)>;
 
 using RemoveAllHistoryCallback = base::OnceCallback<void(const bool)>;
 
diff --git a/vendor/bat-native-ads/src/bat/ads/internal/ads_impl.cc b/vendor/bat-native-ads/src/bat/ads/internal/ads_impl.cc
index 70125d0874f..a5ea0512b50 100644
--- a/vendor/bat-native-ads/src/bat/ads/internal/ads_impl.cc
+++ b/vendor/bat-native-ads/src/bat/ads/internal/ads_impl.cc
@@ -70,10 +70,10 @@ namespace ads {
 
 namespace {
 
-void FailedToInitialize(const InitializeCallback& callback) {
+void FailedToInitialize(InitializeCallback callback) {
   BLOG(1, "Failed to initialize ads");
 
-  callback(/*success*/ false);
+  std::move(callback).Run(/*success*/ false);
 }
 
 }  // namespace
@@ -163,17 +163,17 @@ void AdsImpl::Initialize(InitializeCallback callback) {
 
   if (IsInitialized()) {
     BLOG(1, "Already initialized ads");
-    FailedToInitialize(callback);
+    FailedToInitialize(std::move(callback));
     return;
   }
 
-  CreateOrOpenDatabase(callback);
+  CreateOrOpenDatabase(std::move(callback));
 }
 
 void AdsImpl::Shutdown(ShutdownCallback callback) {
   if (!is_initialized_) {
     BLOG(0, "Shutdown failed as not initialized");
-    callback(/*success*/ false);
+    std::move(callback).Run(/*success*/ false);
     return;
   }
 
@@ -181,7 +181,7 @@ void AdsImpl::Shutdown(ShutdownCallback callback) {
 
   NotificationAdManager::GetInstance()->RemoveAll();
 
-  callback(/*success*/ true);
+  std::move(callback).Run(/*success*/ true);
 }
 
 void AdsImpl::OnLocaleDidChange(const std::string& locale) {
@@ -446,99 +446,101 @@ bool AdsImpl::ToggleSavedAd(base::Value::Dict value) {
 ///////////////////////////////////////////////////////////////////////////////
 
 void AdsImpl::CreateOrOpenDatabase(InitializeCallback callback) {
-  DatabaseManager::GetInstance()->CreateOrOpen(base::BindOnce(
-      &AdsImpl::OnCreateOrOpenDatabase, base::Unretained(this), callback));
+  DatabaseManager::GetInstance()->CreateOrOpen(
+      base::BindOnce(&AdsImpl::OnCreateOrOpenDatabase, base::Unretained(this),
+                     std::move(callback)));
 }
 
-void AdsImpl::OnCreateOrOpenDatabase(const InitializeCallback& callback,
+void AdsImpl::OnCreateOrOpenDatabase(InitializeCallback callback,
                                      const bool success) {
   if (!success) {
     BLOG(0, "Failed to create or open database");
-    FailedToInitialize(callback);
+    FailedToInitialize(std::move(callback));
     return;
   }
 
-  MigrateConversions(callback);
+  conversions::Migrate(base::BindOnce(&AdsImpl::OnMigrateConversions,
+                                      base::Unretained(this),
+                                      std::move(callback)));
 }
 
-void AdsImpl::MigrateConversions(const InitializeCallback& callback) {
-  conversions::Migrate([=](const bool success) {
-    if (!success) {
-      FailedToInitialize(callback);
-      return;
-    }
+void AdsImpl::OnMigrateConversions(InitializeCallback callback,
+                                   const bool success) {
+  if (!success) {
+    FailedToInitialize(std::move(callback));
+    return;
+  }
 
-    MigrateRewards(callback);
-  });
+  rewards::Migrate(base::BindOnce(&AdsImpl::OnMigrateRewards,
+                                  base::Unretained(this), std::move(callback)));
 }
 
-void AdsImpl::MigrateRewards(const InitializeCallback& callback) {
-  rewards::Migrate([=](const bool success) {
-    if (!success) {
-      FailedToInitialize(callback);
-      return;
-    }
+void AdsImpl::OnMigrateRewards(InitializeCallback callback,
+                               const bool success) {
+  if (!success) {
+    FailedToInitialize(std::move(callback));
+    return;
+  }
 
-    MigrateClientState(callback);
-  });
+  client::Migrate(base::BindOnce(&AdsImpl::OnMigrateClientState,
+                                 base::Unretained(this), std::move(callback)));
 }
 
-void AdsImpl::MigrateClientState(const InitializeCallback& callback) {
-  client::Migrate([=](const bool success) {
-    if (!success) {
-      FailedToInitialize(callback);
-      return;
-    }
+void AdsImpl::OnMigrateClientState(InitializeCallback callback,
+                                   const bool success) {
+  if (!success) {
+    FailedToInitialize(std::move(callback));
+    return;
+  }
 
-    LoadClientState(callback);
-  });
+  ClientStateManager::GetInstance()->Initialize(
+      base::BindOnce(&AdsImpl::OnLoadClientState, base::Unretained(this),
+                     std::move(callback)));
 }
 
-void AdsImpl::LoadClientState(const InitializeCallback& callback) {
-  ClientStateManager::GetInstance()->Initialize([=](const bool success) {
-    if (!success) {
-      FailedToInitialize(callback);
-      return;
-    }
+void AdsImpl::OnLoadClientState(InitializeCallback callback,
+                                const bool success) {
+  if (!success) {
+    FailedToInitialize(std::move(callback));
+    return;
+  }
 
-    MigrateConfirmationState(callback);
-  });
+  confirmations::Migrate(base::BindOnce(&AdsImpl::OnMigrateConfirmationState,
+                                        base::Unretained(this),
+                                        std::move(callback)));
 }
 
-void AdsImpl::MigrateConfirmationState(const InitializeCallback& callback) {
-  confirmations::Migrate([=](const bool success) {
-    if (!success) {
-      callback(/*success*/ false);
-      return;
-    }
+void AdsImpl::OnMigrateConfirmationState(InitializeCallback callback,
+                                         const bool success) {
+  if (!success) {
+    FailedToInitialize(std::move(callback));
+    return;
+  }
 
-    LoadConfirmationState(callback);
-  });
+  ConfirmationStateManager::GetInstance()->Initialize(
+      base::BindOnce(&AdsImpl::OnLoadConfirmationState, base::Unretained(this),
+                     std::move(callback)));
 }
 
-void AdsImpl::LoadConfirmationState(const InitializeCallback& callback) {
-  ConfirmationStateManager::GetInstance()->Initialize([=](const bool success) {
-    if (!success) {
-      FailedToInitialize(callback);
-      return;
-    }
+void AdsImpl::OnLoadConfirmationState(InitializeCallback callback,
+                                      const bool success) {
+  if (!success) {
+    FailedToInitialize(std::move(callback));
+    return;
+  }
 
-    MigrateNotificationState(callback);
-  });
+  notifications::Migrate(base::BindOnce(&AdsImpl::OnMigrateNotificationState,
+                                        base::Unretained(this),
+                                        std::move(callback)));
 }
 
-void AdsImpl::MigrateNotificationState(const InitializeCallback& callback) {
-  notifications::Migrate([=](const bool success) {
-    if (!success) {
-      callback(/*success*/ false);
-      return;
-    }
+void AdsImpl::OnMigrateNotificationState(InitializeCallback callback,
+                                         const bool success) {
+  if (!success) {
+    FailedToInitialize(std::move(callback));
+    return;
+  }
 
-    SuccessfullyInitialized(callback);
-  });
-}
-
-void AdsImpl::SuccessfullyInitialized(const InitializeCallback& callback) {
   BLOG(1, "Successfully initialized ads");
 
   is_initialized_ = true;
@@ -546,7 +548,7 @@ void AdsImpl::SuccessfullyInitialized(const InitializeCallback& callback) {
   UserActivityManager::GetInstance()->RecordEvent(
       UserActivityEventType::kInitializedAds);
 
-  callback(/*success*/ true);
+  std::move(callback).Run(/*success*/ true);
 
   Start();
 }
diff --git a/vendor/bat-native-ads/src/bat/ads/internal/ads_impl.h b/vendor/bat-native-ads/src/bat/ads/internal/ads_impl.h
index 59c61f6f532..6493786c941 100644
--- a/vendor/bat-native-ads/src/bat/ads/internal/ads_impl.h
+++ b/vendor/bat-native-ads/src/bat/ads/internal/ads_impl.h
@@ -196,16 +196,15 @@ class AdsImpl final : public Ads,
 
  private:
   void CreateOrOpenDatabase(InitializeCallback callback);
-  void OnCreateOrOpenDatabase(const InitializeCallback& callback, bool success);
-  void MigrateConversions(const InitializeCallback& callback);
-  void MigrateRewards(const InitializeCallback& callback);
-  void MigrateClientState(const InitializeCallback& callback);
-  void LoadClientState(const InitializeCallback& callback);
-  void MigrateConfirmationState(const InitializeCallback& callback);
-  void LoadConfirmationState(const InitializeCallback& callback);
-  void MigrateNotificationState(const InitializeCallback& callback);
+  void OnCreateOrOpenDatabase(InitializeCallback callback, bool success);
+  void OnMigrateConversions(InitializeCallback callback, bool success);
+  void OnMigrateRewards(InitializeCallback callback, bool success);
+  void OnMigrateClientState(InitializeCallback callback, bool success);
+  void OnLoadClientState(InitializeCallback callback, bool success);
+  void OnMigrateConfirmationState(InitializeCallback callback, bool success);
+  void OnLoadConfirmationState(InitializeCallback callback, bool success);
+  void OnMigrateNotificationState(InitializeCallback callback, bool success);
 
-  void SuccessfullyInitialized(const InitializeCallback& callback);
   bool IsInitialized() const;
 
   void Start();
diff --git a/vendor/bat-native-ads/src/bat/ads/internal/base/unittest/unittest_base.cc b/vendor/bat-native-ads/src/bat/ads/internal/base/unittest/unittest_base.cc
index 59b392c5d86..f925dd6f380 100644
--- a/vendor/bat-native-ads/src/bat/ads/internal/base/unittest/unittest_base.cc
+++ b/vendor/bat-native-ads/src/bat/ads/internal/base/unittest/unittest_base.cc
@@ -182,11 +182,11 @@ void UnitTestBase::Initialize() {
 
   client_state_manager_ = std::make_unique<ClientStateManager>();
   client_state_manager_->Initialize(
-      [](const bool success) { ASSERT_TRUE(success); });
+      base::BindOnce([](const bool success) { ASSERT_TRUE(success); }));
 
   confirmation_state_manager_ = std::make_unique<ConfirmationStateManager>();
   confirmation_state_manager_->Initialize(
-      [](const bool success) { ASSERT_TRUE(success); });
+      base::BindOnce([](const bool success) { ASSERT_TRUE(success); }));
 
   covariate_manager_ = std::make_unique<CovariateManager>();
 
@@ -321,15 +321,18 @@ void UnitTestBase::SetUpIntegrationTest() {
          "initialized for integration testing";
 
   ads_ = std::make_unique<AdsImpl>(ads_client_mock_.get());
-  ads_->Initialize([=](const bool success) {
-    ASSERT_TRUE(success);
-
-    ads_->OnRewardsWalletDidChange(
-        /*payment_id*/ "c387c2d8-a26d-4451-83e4-5c0c6fd942be",
-        /*seed*/ "5BEKM1Y7xcRSg/1q8in/+Lki2weFZQB+UMYZlRw8ql8=");
-  });
+  ads_->Initialize(
+      base::BindOnce(&UnitTestBase::OnAdsInitialize, base::Unretained(this)));
 
   task_environment_.RunUntilIdle();
 }
 
+void UnitTestBase::OnAdsInitialize(const bool success) {
+  ASSERT_TRUE(success);
+
+  ads_->OnRewardsWalletDidChange(
+      /*payment_id*/ "c387c2d8-a26d-4451-83e4-5c0c6fd942be",
+      /*seed*/ "5BEKM1Y7xcRSg/1q8in/+Lki2weFZQB+UMYZlRw8ql8=");
+}
+
 }  // namespace ads
diff --git a/vendor/bat-native-ads/src/bat/ads/internal/base/unittest/unittest_base.h b/vendor/bat-native-ads/src/bat/ads/internal/base/unittest/unittest_base.h
index e8a94ed069e..61564695dac 100644
--- a/vendor/bat-native-ads/src/bat/ads/internal/base/unittest/unittest_base.h
+++ b/vendor/bat-native-ads/src/bat/ads/internal/base/unittest/unittest_base.h
@@ -145,6 +145,8 @@ class UnitTestBase : public testing::Test {
 
   void SetUpIntegrationTest();
 
+  void OnAdsInitialize(bool success);
+
   base::ScopedTempDir temp_dir_;
 
   bool is_integration_test_ = false;
diff --git a/vendor/bat-native-ads/src/bat/ads/internal/deprecated/client/client_state_manager.cc b/vendor/bat-native-ads/src/bat/ads/internal/deprecated/client/client_state_manager.cc
index 8f34e07c6b2..a95e88b06d4 100644
--- a/vendor/bat-native-ads/src/bat/ads/internal/deprecated/client/client_state_manager.cc
+++ b/vendor/bat-native-ads/src/bat/ads/internal/deprecated/client/client_state_manager.cc
@@ -137,9 +137,7 @@ const FlaggedAdList& ClientStateManager::GetFlaggedAds() const {
 }
 
 void ClientStateManager::Initialize(InitializeCallback callback) {
-  callback_ = std::move(callback);
-
-  Load();
+  Load(std::move(callback));
 }
 
 void ClientStateManager::AppendHistory(const HistoryItemInfo& history_item) {
@@ -537,15 +535,18 @@ void ClientStateManager::Save() {
                                        base::BindOnce(&OnSaved));
 }
 
-void ClientStateManager::Load() {
+void ClientStateManager::Load(InitializeCallback callback) {
   BLOG(3, "Loading client state");
 
   AdsClientHelper::GetInstance()->Load(
       kClientStateFilename,
-      base::BindOnce(&ClientStateManager::OnLoaded, base::Unretained(this)));
+      base::BindOnce(&ClientStateManager::OnLoaded, base::Unretained(this),
+                     std::move(callback)));
 }
 
-void ClientStateManager::OnLoaded(const bool success, const std::string& json) {
+void ClientStateManager::OnLoaded(InitializeCallback callback,
+                                  const bool success,
+                                  const std::string& json) {
   if (!success) {
     BLOG(3, "Client state does not exist, creating default state");
 
@@ -559,7 +560,7 @@ void ClientStateManager::OnLoaded(const bool success, const std::string& json) {
 
       BLOG(3, "Failed to parse client state: " << json);
 
-      callback_(/*success*/ false);
+      std::move(callback).Run(/*success*/ false);
       return;
     }
 
@@ -573,7 +574,7 @@ void ClientStateManager::OnLoaded(const bool success, const std::string& json) {
     BLOG(9, "Client state is mutated");
   }
 
-  callback_(/*success */ true);
+  std::move(callback).Run(/*success */ true);
 }
 
 bool ClientStateManager::FromJson(const std::string& json) {
diff --git a/vendor/bat-native-ads/src/bat/ads/internal/deprecated/client/client_state_manager.h b/vendor/bat-native-ads/src/bat/ads/internal/deprecated/client/client_state_manager.h
index 878e5b0d79d..997141fee50 100644
--- a/vendor/bat-native-ads/src/bat/ads/internal/deprecated/client/client_state_manager.h
+++ b/vendor/bat-native-ads/src/bat/ads/internal/deprecated/client/client_state_manager.h
@@ -100,8 +100,10 @@ class ClientStateManager final {
  private:
   void Save();
 
-  void Load();
-  void OnLoaded(bool success, const std::string& json);
+  void Load(InitializeCallback callback);
+  void OnLoaded(InitializeCallback callback,
+                bool success,
+                const std::string& json);
 
   bool FromJson(const std::string& json);
 
@@ -110,8 +112,6 @@ class ClientStateManager final {
   bool is_mutated_ = false;
 
   bool is_initialized_ = false;
-
-  InitializeCallback callback_;
 };
 
 }  // namespace ads
diff --git a/vendor/bat-native-ads/src/bat/ads/internal/deprecated/confirmations/confirmation_state_manager.cc b/vendor/bat-native-ads/src/bat/ads/internal/deprecated/confirmations/confirmation_state_manager.cc
index ca28c0fede0..194a2b85d5f 100644
--- a/vendor/bat-native-ads/src/bat/ads/internal/deprecated/confirmations/confirmation_state_manager.cc
+++ b/vendor/bat-native-ads/src/bat/ads/internal/deprecated/confirmations/confirmation_state_manager.cc
@@ -307,25 +307,20 @@ bool ConfirmationStateManager::HasInstance() {
 }
 
 void ConfirmationStateManager::Initialize(InitializeCallback callback) {
-  callback_ = std::move(callback);
+  BLOG(3, "Loading confirmations state");
 
-  Load();
+  AdsClientHelper::GetInstance()->Load(
+      kConfirmationStateFilename,
+      base::BindOnce(&ConfirmationStateManager::OnLoaded,
+                     base::Unretained(this), std::move(callback)));
 }
 
 bool ConfirmationStateManager::IsInitialized() const {
   return is_initialized_;
 }
 
-void ConfirmationStateManager::Load() {
-  BLOG(3, "Loading confirmations state");
-
-  AdsClientHelper::GetInstance()->Load(
-      kConfirmationStateFilename,
-      base::BindOnce(&ConfirmationStateManager::OnLoaded,
-                     base::Unretained(this)));
-}
-
-void ConfirmationStateManager::OnLoaded(const bool success,
+void ConfirmationStateManager::OnLoaded(InitializeCallback callback,
+                                        const bool success,
                                         const std::string& json) {
   if (!success) {
     BLOG(3, "Confirmations state does not exist, creating default state");
@@ -339,7 +334,7 @@ void ConfirmationStateManager::OnLoaded(const bool success,
 
       BLOG(3, "Failed to parse confirmations state: " << json);
 
-      callback_(/*success*/ false);
+      std::move(callback).Run(/*success*/ false);
       return;
     }
 
@@ -353,7 +348,7 @@ void ConfirmationStateManager::OnLoaded(const bool success,
     BLOG(9, "Confirmation state is mutated");
   }
 
-  callback_(/*success*/ true);
+  std::move(callback).Run(/*success*/ true);
 }
 
 void ConfirmationStateManager::Save() {
diff --git a/vendor/bat-native-ads/src/bat/ads/internal/deprecated/confirmations/confirmation_state_manager.h b/vendor/bat-native-ads/src/bat/ads/internal/deprecated/confirmations/confirmation_state_manager.h
index 779c60ad859..752dc35a842 100644
--- a/vendor/bat-native-ads/src/bat/ads/internal/deprecated/confirmations/confirmation_state_manager.h
+++ b/vendor/bat-native-ads/src/bat/ads/internal/deprecated/confirmations/confirmation_state_manager.h
@@ -41,7 +41,6 @@ class ConfirmationStateManager final {
   void Initialize(InitializeCallback callback);
   bool IsInitialized() const;
 
-  void Load();
   void Save();
 
   std::string ToJson();
@@ -65,7 +64,9 @@ class ConfirmationStateManager final {
   bool is_mutated() const { return is_mutated_; }
 
  private:
-  void OnLoaded(bool success, const std::string& json);
+  void OnLoaded(InitializeCallback callback,
+                bool success,
+                const std::string& json);
 
   bool ParseFailedConfirmationsFromDictionary(const base::Value::Dict& dict);
 
@@ -76,7 +77,6 @@ class ConfirmationStateManager final {
   bool is_mutated_ = false;
 
   bool is_initialized_ = false;
-  InitializeCallback callback_;
 
   ConfirmationList failed_confirmations_;
 
diff --git a/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/client/legacy_client_migration.cc b/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/client/legacy_client_migration.cc
index 6f832b8e290..dabab5421fa 100644
--- a/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/client/legacy_client_migration.cc
+++ b/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/client/legacy_client_migration.cc
@@ -6,6 +6,7 @@
 #include "bat/ads/internal/legacy_migration/client/legacy_client_migration.h"
 
 #include <string>
+#include <utility>
 
 #include "base/bind.h"
 #include "bat/ads/internal/ads_client_helper.h"
@@ -19,21 +20,21 @@ namespace ads::client {
 
 namespace {
 
-void FailedToMigrate(const InitializeCallback& callback) {
-  callback(/*success*/ false);
+void FailedToMigrate(InitializeCallback callback) {
+  std::move(callback).Run(/*success*/ false);
 }
 
-void SuccessfullyMigrated(const InitializeCallback& callback) {
+void SuccessfullyMigrated(InitializeCallback callback) {
   AdsClientHelper::GetInstance()->SetBooleanPref(prefs::kHasMigratedClientState,
                                                  true);
-  callback(/*success*/ true);
+  std::move(callback).Run(/*success*/ true);
 }
 
 }  // namespace
 
 void Migrate(InitializeCallback callback) {
   if (HasMigrated()) {
-    callback(/*success*/ true);
+    std::move(callback).Run(/*success*/ true);
     return;
   }
 
@@ -46,14 +47,14 @@ void Migrate(InitializeCallback callback) {
              const std::string& json) {
             if (!success) {
               // Client state does not exist
-              SuccessfullyMigrated(callback);
+              SuccessfullyMigrated(std::move(callback));
               return;
             }
 
             ClientInfo client;
             if (!client.FromJson(json)) {
               BLOG(0, "Failed to load client state");
-              FailedToMigrate(callback);
+              FailedToMigrate(std::move(callback));
               return;
             }
 
@@ -67,19 +68,19 @@ void Migrate(InitializeCallback callback) {
             AdsClientHelper::GetInstance()->Save(
                 kClientStateFilename, migrated_json,
                 base::BindOnce(
-                    [](const InitializeCallback& callback, const bool success) {
+                    [](InitializeCallback callback, const bool success) {
                       if (!success) {
                         BLOG(0, "Failed to save client state");
-                        FailedToMigrate(callback);
+                        FailedToMigrate(std::move(callback));
                         return;
                       }
 
                       BLOG(3, "Successfully migrated client state");
-                      SuccessfullyMigrated(callback);
+                      SuccessfullyMigrated(std::move(callback));
                     },
-                    callback));
+                    std::move(callback)));
           },
-          callback));
+          std::move(callback)));
 }
 
 }  // namespace ads::client
diff --git a/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/client/legacy_client_migration_unittest_util.cc b/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/client/legacy_client_migration_unittest_util.cc
index 8ccc73ae254..fb421f5743c 100644
--- a/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/client/legacy_client_migration_unittest_util.cc
+++ b/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/client/legacy_client_migration_unittest_util.cc
@@ -5,6 +5,7 @@
 
 #include "bat/ads/internal/legacy_migration/client/legacy_client_migration_unittest_util.h"
 
+#include "base/bind.h"
 #include "base/check.h"
 #include "bat/ads/internal/ads_client_helper.h"
 #include "bat/ads/internal/legacy_migration/client/legacy_client_migration.h"
@@ -13,9 +14,11 @@
 namespace ads::client {
 
 void Migrate(const bool should_migrate) {
-  Migrate([should_migrate](const bool success) {
-    CHECK_EQ(success, should_migrate);
-  });
+  Migrate(base::BindOnce(
+      [](const bool should_migrate, const bool success) {
+        CHECK_EQ(success, should_migrate);
+      },
+      should_migrate));
 }
 
 uint64_t GetHash() {
diff --git a/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/confirmations/legacy_confirmation_migration.cc b/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/confirmations/legacy_confirmation_migration.cc
index e47214705a8..7baba6fb90f 100644
--- a/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/confirmations/legacy_confirmation_migration.cc
+++ b/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/confirmations/legacy_confirmation_migration.cc
@@ -6,6 +6,7 @@
 #include "bat/ads/internal/legacy_migration/confirmations/legacy_confirmation_migration.h"
 
 #include <string>
+#include <utility>
 
 #include "base/bind.h"
 #include "bat/ads/internal/ads_client_helper.h"
@@ -19,21 +20,21 @@ namespace ads::confirmations {
 
 namespace {
 
-void FailedToMigrate(const InitializeCallback& callback) {
-  callback(/*success*/ false);
+void FailedToMigrate(InitializeCallback callback) {
+  std::move(callback).Run(/*success*/ false);
 }
 
-void SuccessfullyMigrated(const InitializeCallback& callback) {
+void SuccessfullyMigrated(InitializeCallback callback) {
   AdsClientHelper::GetInstance()->SetBooleanPref(
       prefs::kHasMigratedConfirmationState, true);
-  callback(/*success*/ true);
+  std::move(callback).Run(/*success*/ true);
 }
 
 }  // namespace
 
 void Migrate(InitializeCallback callback) {
   if (HasMigrated()) {
-    callback(/*success*/ true);
+    std::move(callback).Run(/*success*/ true);
     return;
   }
 
@@ -46,13 +47,13 @@ void Migrate(InitializeCallback callback) {
              const std::string& json) {
             if (!success) {
               // Confirmation state does not exist
-              SuccessfullyMigrated(callback);
+              SuccessfullyMigrated(std::move(callback));
               return;
             }
 
             if (!ConfirmationStateManager::GetInstance()->FromJson(json)) {
               BLOG(0, "Failed to load confirmation state");
-              FailedToMigrate(callback);
+              FailedToMigrate(std::move(callback));
               return;
             }
 
@@ -67,19 +68,19 @@ void Migrate(InitializeCallback callback) {
             AdsClientHelper::GetInstance()->Save(
                 kConfirmationStateFilename, migrated_json,
                 base::BindOnce(
-                    [](const InitializeCallback& callback, const bool success) {
+                    [](InitializeCallback callback, const bool success) {
                       if (!success) {
                         BLOG(0, "Failed to save confirmation state");
-                        FailedToMigrate(callback);
+                        FailedToMigrate(std::move(callback));
                         return;
                       }
 
                       BLOG(3, "Successfully migrated confirmation state");
-                      SuccessfullyMigrated(callback);
+                      SuccessfullyMigrated(std::move(callback));
                     },
-                    callback));
+                    std::move(callback)));
           },
-          callback));
+          std::move(callback)));
 }
 
 }  // namespace ads::confirmations
diff --git a/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/confirmations/legacy_confirmation_migration_unittest_util.cc b/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/confirmations/legacy_confirmation_migration_unittest_util.cc
index 06c9f7963d2..b4c7be31071 100644
--- a/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/confirmations/legacy_confirmation_migration_unittest_util.cc
+++ b/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/confirmations/legacy_confirmation_migration_unittest_util.cc
@@ -5,6 +5,7 @@
 
 #include "bat/ads/internal/legacy_migration/confirmations/legacy_confirmation_migration_unittest_util.h"
 
+#include "base/bind.h"
 #include "base/check_op.h"
 #include "bat/ads/internal/ads_client_helper.h"
 #include "bat/ads/internal/legacy_migration/confirmations/legacy_confirmation_migration.h"
@@ -13,9 +14,11 @@
 namespace ads::confirmations {
 
 void Migrate(const bool should_migrate) {
-  Migrate([should_migrate](const bool success) {
-    CHECK_EQ(success, should_migrate);
-  });
+  Migrate(base::BindOnce(
+      [](const bool should_migrate, const bool success) {
+        CHECK_EQ(success, should_migrate);
+      },
+      should_migrate));
 }
 
 uint64_t GetHash() {
diff --git a/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/conversions/legacy_conversions_migration.cc b/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/conversions/legacy_conversions_migration.cc
index 4d52b2ea3aa..f82ddba4736 100644
--- a/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/conversions/legacy_conversions_migration.cc
+++ b/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/conversions/legacy_conversions_migration.cc
@@ -6,6 +6,7 @@
 #include "bat/ads/internal/legacy_migration/conversions/legacy_conversions_migration.h"
 
 #include <string>
+#include <utility>
 
 #include "absl/types/optional.h"
 #include "base/bind.h"
@@ -34,14 +35,14 @@ bool HasMigrated() {
       prefs::kHasMigratedConversionState);
 }
 
-void FailedToMigrate(const InitializeCallback& callback) {
-  callback(/*success*/ false);
+void FailedToMigrate(InitializeCallback callback) {
+  std::move(callback).Run(/*success*/ false);
 }
 
-void SuccessfullyMigrated(const InitializeCallback& callback) {
+void SuccessfullyMigrated(InitializeCallback callback) {
   AdsClientHelper::GetInstance()->SetBooleanPref(
       prefs::kHasMigratedConversionState, true);
-  callback(/*success*/ true);
+  std::move(callback).Run(/*success*/ true);
 }
 
 absl::optional<ConversionQueueItemInfo> GetFromDictionary(
@@ -121,7 +122,7 @@ void OnMigrate(InitializeCallback callback,
                const std::string& json) {
   if (!success) {
     // Conversion state does not exist
-    SuccessfullyMigrated(callback);
+    SuccessfullyMigrated(std::move(callback));
     return;
   }
 
@@ -129,7 +130,7 @@ void OnMigrate(InitializeCallback callback,
       FromJson(json);
   if (!conversion_queue_items) {
     BLOG(0, "Failed to parse conversion state");
-    FailedToMigrate(callback);
+    FailedToMigrate(std::move(callback));
     return;
   }
 
@@ -141,31 +142,31 @@ void OnMigrate(InitializeCallback callback,
   conversion_queue.Save(
       *conversion_queue_items,
       base::BindOnce(
-          [](const InitializeCallback& callback, const bool success) {
+          [](InitializeCallback callback, const bool success) {
             if (!success) {
               BLOG(0, "Failed to save conversion state");
-              FailedToMigrate(callback);
+              FailedToMigrate(std::move(callback));
               return;
             }
 
             BLOG(3, "Successfully migrated conversion state");
-            SuccessfullyMigrated(callback);
+            SuccessfullyMigrated(std::move(callback));
           },
-          callback));
+          std::move(callback)));
 }
 
 }  // namespace
 
 void Migrate(InitializeCallback callback) {
   if (HasMigrated()) {
-    callback(/*success*/ true);
+    std::move(callback).Run(/*success*/ true);
     return;
   }
 
   BLOG(3, "Loading conversion state");
 
-  AdsClientHelper::GetInstance()->Load(kFilename,
-                                       base::BindOnce(&OnMigrate, callback));
+  AdsClientHelper::GetInstance()->Load(
+      kFilename, base::BindOnce(&OnMigrate, std::move(callback)));
 }
 
 }  // namespace ads::conversions
diff --git a/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/notifications/legacy_notification_migration.cc b/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/notifications/legacy_notification_migration.cc
index 6df3350c91a..edc322f5a22 100644
--- a/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/notifications/legacy_notification_migration.cc
+++ b/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/notifications/legacy_notification_migration.cc
@@ -6,6 +6,7 @@
 #include "bat/ads/internal/legacy_migration/notifications/legacy_notification_migration.h"
 
 #include <string>
+#include <utility>
 
 #include "absl/types/optional.h"
 #include "base/bind.h"
@@ -28,21 +29,21 @@ bool HasMigrated() {
       prefs::kHasMigratedNotificationState);
 }
 
-void FailedToMigrate(const InitializeCallback& callback) {
-  callback(/*success*/ false);
+void FailedToMigrate(InitializeCallback callback) {
+  std::move(callback).Run(/*success*/ false);
 }
 
-void SuccessfullyMigrated(const InitializeCallback& callback) {
+void SuccessfullyMigrated(InitializeCallback callback) {
   AdsClientHelper::GetInstance()->SetBooleanPref(
       prefs::kHasMigratedNotificationState, true);
-  callback(/*success*/ true);
+  std::move(callback).Run(/*success*/ true);
 }
 
 }  // namespace
 
 void Migrate(InitializeCallback callback) {
   if (HasMigrated()) {
-    callback(/*success*/ true);
+    std::move(callback).Run(/*success*/ true);
     return;
   }
 
@@ -51,11 +52,11 @@ void Migrate(InitializeCallback callback) {
   AdsClientHelper::GetInstance()->Load(
       kNotificationStateFilename,
       base::BindOnce(
-          [](const InitializeCallback& callback, const bool success,
+          [](InitializeCallback callback, const bool success,
              const std::string& json) {
             if (!success) {
               // Notification state does not exist
-              SuccessfullyMigrated(callback);
+              SuccessfullyMigrated(std::move(callback));
               return;
             }
 
@@ -63,7 +64,7 @@ void Migrate(InitializeCallback callback) {
                 json::reader::ReadNotificationAds(json);
             if (!ads) {
               BLOG(0, "Failed to load notification state");
-              FailedToMigrate(callback);
+              FailedToMigrate(std::move(callback));
               return;
             }
 
@@ -75,9 +76,9 @@ void Migrate(InitializeCallback callback) {
                 prefs::kNotificationAds, NotificationAdsToValue(*ads));
 
             BLOG(3, "Successfully migrated notification state");
-            SuccessfullyMigrated(callback);
+            SuccessfullyMigrated(std::move(callback));
           },
-          callback));
+          std::move(callback)));
 }
 
 }  // namespace ads::notifications
diff --git a/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/rewards/legacy_rewards_migration.cc b/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/rewards/legacy_rewards_migration.cc
index ea96060a5e5..e31260f8c48 100644
--- a/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/rewards/legacy_rewards_migration.cc
+++ b/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/rewards/legacy_rewards_migration.cc
@@ -6,6 +6,7 @@
 #include "bat/ads/internal/legacy_migration/rewards/legacy_rewards_migration.h"
 
 #include <string>
+#include <utility>
 
 #include "absl/types/optional.h"
 #include "base/bind.h"
@@ -26,14 +27,14 @@ bool HasMigrated() {
       prefs::kHasMigratedRewardsState);
 }
 
-void FailedToMigrate(const InitializeCallback& callback) {
-  callback(/*success*/ false);
+void FailedToMigrate(InitializeCallback callback) {
+  std::move(callback).Run(/*success*/ false);
 }
 
-void SuccessfullyMigrated(const InitializeCallback& callback) {
+void SuccessfullyMigrated(InitializeCallback callback) {
   AdsClientHelper::GetInstance()->SetBooleanPref(
       prefs::kHasMigratedRewardsState, true);
-  callback(/*success*/ true);
+  std::move(callback).Run(/*success*/ true);
 }
 
 void OnMigrate(InitializeCallback callback,
@@ -41,7 +42,7 @@ void OnMigrate(InitializeCallback callback,
                const std::string& json) {
   if (!success) {
     // Confirmations state does not exist
-    SuccessfullyMigrated(callback);
+    SuccessfullyMigrated(std::move(callback));
     return;
   }
 
@@ -53,39 +54,39 @@ void OnMigrate(InitializeCallback callback,
       BuildTransactionsFromJson(json);
   if (!transactions) {
     BLOG(0, "Failed to parse rewards state");
-    FailedToMigrate(callback);
+    FailedToMigrate(std::move(callback));
     return;
   }
 
   database::table::Transactions database_table;
-  database_table.Save(
-      *transactions,
-      base::BindOnce(
-          [](const InitializeCallback& callback, const bool success) {
-            if (!success) {
-              BLOG(0, "Failed to save rewards state");
-              FailedToMigrate(callback);
-              return;
-            }
+  database_table.Save(*transactions,
+                      base::BindOnce(
+                          [](InitializeCallback callback, const bool success) {
+                            if (!success) {
+                              BLOG(0, "Failed to save rewards state");
+                              FailedToMigrate(std::move(callback));
+                              return;
+                            }
 
-            BLOG(3, "Successfully migrated rewards state");
-            SuccessfullyMigrated(callback);
-          },
-          callback));
+                            BLOG(3, "Successfully migrated rewards state");
+                            SuccessfullyMigrated(std::move(callback));
+                          },
+                          std::move(callback)));
 }
 
 }  // namespace
 
 void Migrate(InitializeCallback callback) {
   if (HasMigrated()) {
-    callback(/*success*/ true);
+    std::move(callback).Run(/*success*/ true);
     return;
   }
 
   BLOG(3, "Loading confirmations state");
 
-  AdsClientHelper::GetInstance()->Load(kConfirmationStateFilename,
-                                       base::BindOnce(&OnMigrate, callback));
+  AdsClientHelper::GetInstance()->Load(
+      kConfirmationStateFilename,
+      base::BindOnce(&OnMigrate, std::move(callback)));
 }
 
 }  // namespace ads::rewards
diff --git a/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/rewards/legacy_rewards_migration_issue_25384_unittest.cc b/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/rewards/legacy_rewards_migration_issue_25384_unittest.cc
index 94a2650050b..3341a1c96c8 100644
--- a/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/rewards/legacy_rewards_migration_issue_25384_unittest.cc
+++ b/vendor/bat-native-ads/src/bat/ads/internal/legacy_migration/rewards/legacy_rewards_migration_issue_25384_unittest.cc
@@ -5,6 +5,7 @@
 
 #include "bat/ads/internal/legacy_migration/rewards/legacy_rewards_migration.h"
 
+#include "base/bind.h"
 #include "bat/ads/internal/base/unittest/unittest_base.h"
 #include "bat/ads/internal/deprecated/confirmations/confirmation_state_manager_constants.h"
 #include "brave/components/brave_ads/common/pref_names.h"
@@ -35,7 +36,8 @@ TEST_F(BatAdsLegacyRewardsMigrationIssue25384Test, Migrate) {
   EXPECT_CALL(*ads_client_mock_, Load(kConfirmationStateFilename, _));
 
   // Act
-  rewards::Migrate([=](const bool success) { ASSERT_TRUE(success); });
+  rewards::Migrate(
+      base::BindOnce([](const bool success) { ASSERT_TRUE(success); }));
 
   // Assert
   EXPECT_TRUE(