[NTP Snippets] Persist snippets in a LevelDB instead of prefs

ios/chrome/browser/ntp_snippets/ios_chrome_ntp_snippets_service_factory.cc

Index: ios/chrome/browser/ntp_snippets/ios_chrome_ntp_snippets_service_factory.cc
diff --git a/ios/chrome/browser/ntp_snippets/ios_chrome_ntp_snippets_service_factory.cc b/ios/chrome/browser/ntp_snippets/ios_chrome_ntp_snippets_service_factory.cc
index e57b3321689c0403537eaa0d496727f2231a61cc..8fee9ff42054b26e2a3a47409ffcb1f77f3b2d09 100644
--- a/ios/chrome/browser/ntp_snippets/ios_chrome_ntp_snippets_service_factory.cc
+++ b/ios/chrome/browser/ntp_snippets/ios_chrome_ntp_snippets_service_factory.cc
@@ -4,6 +4,7 @@
 
 #include "ios/chrome/browser/ntp_snippets/ios_chrome_ntp_snippets_service_factory.h"
 
+#include "base/files/file_path.h"
 #include "base/json/json_reader.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/singleton.h"
@@ -12,6 +13,7 @@
 #include "components/browser_sync/browser/profile_sync_service.h"
 #include "components/image_fetcher/image_fetcher.h"
 #include "components/keyed_service/ios/browser_state_dependency_manager.h"
+#include "components/ntp_snippets/ntp_snippets_database.h"
 #include "components/ntp_snippets/ntp_snippets_fetcher.h"
 #include "components/ntp_snippets/ntp_snippets_service.h"
 #include "components/signin/core/browser/signin_manager.h"
@@ -98,18 +100,23 @@ IOSChromeNTPSnippetsServiceFactory::BuildServiceInstanceFor(
 
   ntp_snippets::NTPSnippetsScheduler* scheduler = nullptr;
 
+  base::FilePath database_dir(
+      browser_state->GetStatePath().Append(FILE_PATH_LITERAL("NTPSnippets")));
   scoped_refptr<base::SequencedTaskRunner> task_runner =
       web::WebThread::GetBlockingPool()
           ->GetSequencedTaskRunnerWithShutdownBehavior(
               base::SequencedWorkerPool::GetSequenceToken(),
               base::SequencedWorkerPool::CONTINUE_ON_SHUTDOWN);
+
   return base::WrapUnique(new ntp_snippets::NTPSnippetsService(
       chrome_browser_state->GetPrefs(), sync_service, suggestions_service,
-      task_runner, GetApplicationContext()->GetApplicationLocale(), scheduler,
+      GetApplicationContext()->GetApplicationLocale(), scheduler,
       base::WrapUnique(new ntp_snippets::NTPSnippetsFetcher(
           signin_manager, token_service, request_context,
           base::Bind(&ParseJson),
           GetChannel() == version_info::Channel::STABLE)),
-      base::WrapUnique(new ImageFetcherImpl(
-          request_context.get(), web::WebThread::GetBlockingPool()))));
+      base::WrapUnique(new ImageFetcherImpl(request_context.get(),
+                                            web::WebThread::GetBlockingPool())),
+      base::WrapUnique(
+          new ntp_snippets::NTPSnippetsDatabase(database_dir, task_runner))));
 }