[NTP Snippets] Add a pref to disable the NTPSnippetsService

components/ntp_snippets/ntp_snippets_service.h

 // 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.
 
 #ifndef COMPONENTS_NTP_SNIPPETS_NTP_SNIPPETS_SERVICE_H_
 #define COMPONENTS_NTP_SNIPPETS_NTP_SNIPPETS_SERVICE_H_
 
 #include <stddef.h>
 
 #include <memory>
@@ skipping 204 matching lines @@
   void StoreSnippetHostsToPrefs(const std::set<std::string>& hosts);
 
   // Removes the expired snippets (including discarded) from the service and the
   // database, and schedules another pass for the next expiration.
   void ClearExpiredSnippets();
 
   // Completes the initialization phase of the service, registering the last
   // observers. This is done after construction, once the database is loaded.
   void FinishInitialization();
 
-  void LoadingSnippetsFinished();

[Marc Treib, 2016/07/19 14:50:56]

unrelated: no implementation

-
   void OnSnippetImageFetchedFromDatabase(const std::string& snippet_id,
                                          const ImageFetchedCallback& callback,
                                          std::string data);
 
   void OnSnippetImageDecoded(const std::string& snippet_id,
                              const ImageFetchedCallback& callback,
                              const gfx::Image& image);
 
   void FetchSnippetImageFromNetwork(const std::string& snippet_id,
                                     const ImageFetchedCallback& callback);
 
   // Triggers a state transition depending on the provided reason to be
   // disabled (or lack thereof). This method is called when a change is detected
   // by |snippets_status_service_|.
-  void UpdateStateForStatus(DisabledReason disabled_reason);

[Marc Treib, 2016/07/19 14:50:56]

unrelated: confusing name

+  void OnDisabledReasonChanged(DisabledReason disabled_reason);
 
   // Verifies state transitions (see |State|'s documentation) and applies them.
   // Also updates the provider status. Does nothing except updating the provider
   // status if called with the current state.
   void EnterState(State state, ContentSuggestionsCategoryStatus status);
 
   // Enables the service and triggers a fetch if required. Do not call directly,
   // use |EnterState| instead.
   void EnterStateEnabled(bool fetch_snippets);
 
@@ skipping 84 matching lines @@
   // If the service might be enabled, DisabledReason::NONE will be provided.
   virtual void NTPSnippetsServiceDisabledReasonChanged(DisabledReason) = 0;
 
  protected:
   virtual ~NTPSnippetsServiceObserver() {}
 };
 
 }  // namespace ntp_snippets
 
 #endif  // COMPONENTS_NTP_SNIPPETS_NTP_SNIPPETS_SERVICE_H_