[NTP::Cleanup] Avoid nested complex function calls

ios/chrome/browser/ntp_snippets/ios_chrome_content_suggestions_service_factory.cc

Index: ios/chrome/browser/ntp_snippets/ios_chrome_content_suggestions_service_factory.cc
diff --git a/ios/chrome/browser/ntp_snippets/ios_chrome_content_suggestions_service_factory.cc b/ios/chrome/browser/ntp_snippets/ios_chrome_content_suggestions_service_factory.cc
index 5df921a2197792f5777aed78dc80da4643e89c40..72baf80d377dadb6d5894b8109be651dae91c83b 100644
--- a/ios/chrome/browser/ntp_snippets/ios_chrome_content_suggestions_service_factory.cc
+++ b/ios/chrome/browser/ntp_snippets/ios_chrome_content_suggestions_service_factory.cc
@@ -154,22 +154,27 @@ IOSChromeContentSuggestionsServiceFactory::BuildServiceInstanceFor(
             ->GetSequencedTaskRunnerWithShutdownBehavior(
                 base::SequencedWorkerPool::GetSequenceToken(),
                 base::SequencedWorkerPool::CONTINUE_ON_SHUTDOWN);
-    auto provider = base::MakeUnique<RemoteSuggestionsProviderImpl>(
-        service.get(), prefs, GetApplicationContext()->GetApplicationLocale(),
-        service->category_ranker(),
-        base::MakeUnique<RemoteSuggestionsFetcher>(
-            signin_manager, token_service, request_context, prefs, nullptr,
-            base::Bind(&ParseJson),
-            GetChannel() == version_info::Channel::STABLE
-                ? google_apis::GetAPIKey()
-                : google_apis::GetNonStableAPIKey(),
-            service->user_classifier()),
-        base::MakeUnique<ImageFetcherImpl>(request_context.get(),
-                                           web::WebThread::GetBlockingPool()),
-        CreateIOSImageDecoder(task_runner),
-        base::MakeUnique<RemoteSuggestionsDatabase>(database_dir, task_runner),
-        base::MakeUnique<RemoteSuggestionsStatusService>(signin_manager,
-                                                         prefs));
+
+    std::unique_ptr<RemoteSuggestionsProviderImpl> provider;
+    {
+      auto suggestions_fetcher = base::MakeUnique<RemoteSuggestionsFetcher>(
+          signin_manager, token_service, request_context, prefs, nullptr,
+          base::Bind(&ParseJson), GetChannel() == version_info::Channel::STABLE
+                                      ? google_apis::GetAPIKey()
+                                      : google_apis::GetNonStableAPIKey(),
+          service->user_classifier());
+      auto image_fetcher = base::MakeUnique<ImageFetcherImpl>(
+          request_context.get(), web::WebThread::GetBlockingPool());
+      auto database = base::MakeUnique<RemoteSuggestionsDatabase>(database_dir,
+                                                                  task_runner);
+      auto status_service = base::MakeUnique<RemoteSuggestionsStatusService>(
+          signin_manager, prefs);
+      provider = base::MakeUnique<RemoteSuggestionsProviderImpl>(
+          service.get(), prefs, GetApplicationContext()->GetApplicationLocale(),
+          service->category_ranker(), std::move(suggestions_fetcher),
+          std::move(image_fetcher), CreateIOSImageDecoder(task_runner),
+          std::move(database), std::move(status_service));
+    }
 
     // TODO(jkrcal): Implement a persistent scheduler for iOS. crbug.com/676249
     auto scheduling_provider =