[NTP Snippets] Persist the set of snippets in a pref

chrome/browser/ntp_snippets/ntp_snippets_service_factory.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ntp_snippets/ntp_snippets_service_factory.h"
 
 #include "base/logging.h"
 #include "base/memory/singleton.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/profiles/profile.h"
@@ skipping 50 matching lines @@
   scheduler = NTPSnippetsLauncher::Get();
 #endif  // OS_ANDROID
 
   scoped_refptr<base::SequencedTaskRunner> task_runner =
       BrowserThread::GetBlockingPool()
           ->GetSequencedTaskRunnerWithShutdownBehavior(
               base::SequencedWorkerPool::GetSequenceToken(),
               base::SequencedWorkerPool::CONTINUE_ON_SHUTDOWN);
 
   return new ntp_snippets::NTPSnippetsService(
-      task_runner, g_browser_process->GetApplicationLocale(), scheduler,
+      profile->GetPrefs(), task_runner,
+      g_browser_process->GetApplicationLocale(), scheduler,
       make_scoped_ptr(new ntp_snippets::NTPSnippetsFetcher(
           task_runner, signin_manager, token_service, request_context,
           profile->GetPath())));
 }