[NTP Snippets] Add a pref to disable the NTPSnippetsService

components/ntp_snippets/ntp_snippets_service.h

Index: components/ntp_snippets/ntp_snippets_service.h
diff --git a/components/ntp_snippets/ntp_snippets_service.h b/components/ntp_snippets/ntp_snippets_service.h
index b3c113a1a2dc18dd9f125e92ccd5d61877da5a91..9b2562d9a55db40f8d66053817da38e47ef6306e 100644
--- a/components/ntp_snippets/ntp_snippets_service.h
+++ b/components/ntp_snippets/ntp_snippets_service.h
@@ -222,8 +222,6 @@ class NTPSnippetsService : public KeyedService,
   // 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);
@@ -238,7 +236,7 @@ class NTPSnippetsService : public KeyedService,
   // 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