Snippets are enabled when search suggestions are enabled.

chrome/browser/profiles/profile_manager.cc

 // Copyright (c) 2012 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/profiles/profile_manager.h"
 
 #include <stdint.h>
 
 #include <set>
 #include <string>
@@ skipping 90 matching lines @@
 #endif
 
 #if defined(ENABLE_SUPERVISED_USERS)
 #include "chrome/browser/supervised_user/child_accounts/child_account_service.h"
 #include "chrome/browser/supervised_user/child_accounts/child_account_service_factory.h"
 #include "chrome/browser/supervised_user/supervised_user_service.h"
 #include "chrome/browser/supervised_user/supervised_user_service_factory.h"
 #endif
 
 #if defined(OS_ANDROID)
-#include "chrome/browser/android/chrome_feature_list.h"
 #include "chrome/browser/ntp_snippets/ntp_snippets_service_factory.h"
 #include "components/ntp_snippets/ntp_snippets_service.h"
 #endif
 
 #if defined(OS_CHROMEOS)
 #include "chrome/browser/browser_process_platform_part_chromeos.h"
 #include "chrome/browser/chromeos/profiles/profile_helper.h"
 #include "chromeos/chromeos_switches.h"
 #include "chromeos/dbus/cryptohome_client.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
@@ skipping 1101 matching lines @@
   // Service is responsible for migration of the legacy password manager
   // preference which controls behaviour of the Chrome to the new preference
   // which controls password management behaviour on Chrome and Android. After
   // migration will be performed for all users it's planned to remove the
   // migration code, rough time estimates are Q1 2016.
   PasswordManagerSettingMigratorServiceFactory::GetForProfile(profile)
       ->InitializeMigration(ProfileSyncServiceFactory::GetForProfile(profile));
 
 #if defined(OS_ANDROID)
   // Service is responsible for fetching content snippets for the NTP.
   // Note: Create the service even if the feature is disabled, so that any

[Michael van Ouwerkerk, 2016/05/20 12:38:36]

Marc, I don't understand this comment. Could you maybe suggest a rephrasing that
explains why we're instantiating the service even if it might be disabled?

[Marc Treib, 2016/05/20 13:49:36]

When the service is instantiated and enabled, it schedules a persistent and
recurring task for background fetching, at the Android OS level.
If the service gets disabled later, and we wouldn't instantiate it anymore, then
that task would remain active and would continue to wake up the device.

Does that clear things up?

   // remaining tasks will be cleaned up.
-  NTPSnippetsServiceFactory::GetForProfile(profile)->Init(
-      base::FeatureList::IsEnabled(chrome::android::kNTPSnippetsFeature));
+  NTPSnippetsServiceFactory::GetForProfile(profile)->Init();

[noyau (Ping after 24h), 2016/05/20 15:16:53]

Here the service is created and Init is called right away. Why do we need Init
in the first place? Can't the service "init" itself?

This Init pattern is not something I see used in KeyedServices, and it seems
more error prone than needed.

[noyau (Ping after 24h), 2016/05/24 14:19:11]

Ping!

[Michael van Ouwerkerk, 2016/05/24 14:38:54]

I don't know exactly why. It's possible some of the work done in Init requires a
fully constructed instance, but it's not documented... so now it's gone.

[Michael van Ouwerkerk, 2016/05/24 14:38:54]

Done.

[Bernhard Bauer, 2016/05/24 14:54:28]

The reason why this is here is because we need to start scheduling fetches as
soon as the browser starts. We could achieve this though by overriding
ServiceWillBeCreatedWithProfile in the factory and doing everything from Init()
in the constructor.

[Michael van Ouwerkerk, 2016/05/24 15:00:45]

I just moved everything to the constructor, I expect that's fine?

 #endif
 }
 
 void ProfileManager::DoFinalInitLogging(Profile* profile) {
   TRACE_EVENT0("browser", "ProfileManager::DoFinalInitLogging");
   // Count number of extensions in this profile.
   int enabled_app_count = -1;
 #if defined(ENABLE_EXTENSIONS)
   enabled_app_count = GetEnabledAppCount(profile);
 #endif
@@ skipping 393 matching lines @@
 
   FinishDeletingProfile(profile_to_delete_path, new_active_profile_path);
   if (!original_callback.is_null())
     original_callback.Run(loaded_profile, status);
 }
 #endif  // !defined(OS_ANDROID)
 
 ProfileManagerWithoutInit::ProfileManagerWithoutInit(
     const base::FilePath& user_data_dir) : ProfileManager(user_data_dir) {
 }