SuggestionsService: implement SyncServiceObserver

components/suggestions/suggestions_utils.h

-// Copyright 2014 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_SUGGESTIONS_SUGGESTIONS_UTILS_H_
-#define COMPONENTS_SUGGESTIONS_SUGGESTIONS_UTILS_H_
-
-namespace suggestions {
-
-// Establishes the different sync states that users of SuggestionsService can
-// specify. There are three different concepts in the sync service: initialized,
-// sync enabled and history sync enabled.
-enum SyncState {
-  // State: Sync service is not initialized, yet not disabled. History sync
-  //     state is unknown (since not initialized).
-  // Behavior: Does not issue a server request, but serves from cache if
-  //     available.
-  NOT_INITIALIZED_ENABLED,
-
-  // State: Sync service is initialized, sync is enabled and history sync is
-  //     enabled.
-  // Behavior: Update suggestions from the server. Serve from cache on timeout.
-  INITIALIZED_ENABLED_HISTORY,
-
-  // State: Sync service is disabled or history sync is disabled.
-  // Behavior: Do not issue a server request. Clear the cache. Serve empty
-  //     suggestions.
-  SYNC_OR_HISTORY_SYNC_DISABLED,
-};
-
-// Users of SuggestionsService should always use this function to get SyncState.
-// Note: In chrome/browser/search/suggestions/suggestions_utils.h, there is
-// another variant of this function that takes a Profile* instead.
-SyncState GetSyncState(bool sync_enabled,
-                       bool sync_initialized,
-                       bool history_sync_enabled);
-
-}  // namespace suggestions
-
-#endif  // COMPONENTS_SUGGESTIONS_SUGGESTIONS_UTILS_H_