Snippets are enabled when search suggestions are enabled.

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/feature_list.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/singleton.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/search/suggestions/image_fetcher_impl.h"
 #include "chrome/browser/search/suggestions/suggestions_service_factory.h"
 #include "chrome/browser/signin/profile_oauth2_token_service_factory.h"
 #include "chrome/browser/signin/signin_manager_factory.h"
 #include "chrome/common/channel_info.h"
+#include "chrome/common/pref_names.h"
 #include "components/image_fetcher/image_fetcher.h"
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
 #include "components/ntp_snippets/ntp_snippets_fetcher.h"
 #include "components/ntp_snippets/ntp_snippets_scheduler.h"
 #include "components/ntp_snippets/ntp_snippets_service.h"
+#include "components/prefs/pref_service.h"
 #include "components/safe_json/safe_json_parser.h"
 #include "components/signin/core/browser/profile_oauth2_token_service.h"
 #include "components/signin/core/browser/signin_manager.h"
 #include "components/version_info/version_info.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/storage_partition.h"
 #include "net/url_request/url_request_context_getter.h"
 
 #if defined(OS_ANDROID)
+#include "chrome/browser/android/chrome_feature_list.h"
 #include "chrome/browser/android/ntp/ntp_snippets_launcher.h"
 #endif  // OS_ANDROID
 
 using content::BrowserThread;
 using suggestions::ImageFetcherImpl;
 using suggestions::SuggestionsService;
 using suggestions::SuggestionsServiceFactory;
 
 // static
 NTPSnippetsServiceFactory* NTPSnippetsServiceFactory::GetInstance() {
@@ skipping 15 matching lines @@
   DependsOn(ProfileOAuth2TokenServiceFactory::GetInstance());
   DependsOn(SigninManagerFactory::GetInstance());
   DependsOn(SuggestionsServiceFactory::GetInstance());
 }
 
 NTPSnippetsServiceFactory::~NTPSnippetsServiceFactory() {}
 
 KeyedService* NTPSnippetsServiceFactory::BuildServiceInstanceFor(
     content::BrowserContext* context) const {
   Profile* profile = Profile::FromBrowserContext(context);
+
+  bool enabled = profile->GetPrefs()->GetBoolean(prefs::kSearchSuggestEnabled);
+#if defined(OS_ANDROID)
+  enabled = enabled &&
+            base::FeatureList::IsEnabled(chrome::android::kNTPSnippetsFeature);

[Bernhard Bauer, 2016/05/20 10:43:24]

Hm... both of these things use APIs that are available in components/, just the
keys (prefs::kSearchSuggestEnabled / chrome::android::kNTPSnippetsFeature) are
from chrome/. We could think about moving this into the component as well and
just passing the keys in. That might be particularly interesting once we start
observing pref changes, as then the NTPSnippetsService could observe the pref
directly and we wouldn't have to have an additional object for that.

[Michael van Ouwerkerk, 2016/05/20 11:25:58]

Agreed. I've added a TODO along those lines.

+#endif  // OS_ANDROID
+
   SigninManagerBase* signin_manager =
       SigninManagerFactory::GetForProfile(profile);
   OAuth2TokenService* token_service =
       ProfileOAuth2TokenServiceFactory::GetForProfile(profile);
   scoped_refptr<net::URLRequestContextGetter> request_context =
       content::BrowserContext::GetDefaultStoragePartition(context)->
             GetURLRequestContext();
   SuggestionsService* suggestions_service =
       SuggestionsServiceFactory::GetForProfile(profile);
 
   ntp_snippets::NTPSnippetsScheduler* scheduler = nullptr;
 #if defined(OS_ANDROID)
   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(
-      profile->GetPrefs(), suggestions_service, task_runner,
+      enabled, profile->GetPrefs(), suggestions_service, task_runner,
       g_browser_process->GetApplicationLocale(), scheduler,
       base::WrapUnique(new ntp_snippets::NTPSnippetsFetcher(
           signin_manager, token_service, request_context,
           base::Bind(&safe_json::SafeJsonParser::Parse),
           chrome::GetChannel() == version_info::Channel::STABLE)),
       base::WrapUnique(new ImageFetcherImpl(request_context.get())));
 }