[Sync] Inject startup dependencies into StartupController.

components/sync_driver/startup_controller.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_SYNC_DRIVER_STARTUP_CONTROLLER_H_
 #define COMPONENTS_SYNC_DRIVER_STARTUP_CONTROLLER_H_
 
 #include "base/callback.h"
 #include "base/memory/weak_ptr.h"
 #include "base/time/time.h"
 #include "sync/internal_api/public/base/model_type.h"
 
-class ProfileOAuth2TokenService;
-class SigninManagerWrapper;
-
 namespace sync_driver {
 class SyncPrefs;
 }
 
 namespace browser_sync {
 
 // This class is used by ProfileSyncService to manage all logic and state
 // pertaining to initialization of the SyncBackendHost (colloquially referred
 // to as "the backend").
 class StartupController {
  public:
-  StartupController(const ProfileOAuth2TokenService* token_service,
-                    const sync_driver::SyncPrefs* sync_prefs,
-                    const SigninManagerWrapper* signin,
+  StartupController(const sync_driver::SyncPrefs* sync_prefs,
+                    base::Callback<bool()> can_start,
                     base::Closure start_backend);
   ~StartupController();
 
   // Starts up sync if it is requested by the user and preconditions are met.
   // Returns true if these preconditions are met, although does not imply
   // the backend was started.
   bool TryStart();
 
   // Called when a datatype (SyncableService) has a need for sync to start
   // ASAP, presumably because a local change event has occurred but we're
@@ skipping 42 matching lines @@
 
   // If |true|, there is setup UI visible so we should not start downloading
   // data types.
   // Note: this is explicitly controlled by higher layers (UI) and is meant to
   // reflect what the UI claims the setup state to be. Therefore, only set this
   // due to explicit requests to do so via SetSetupInProgress.
   bool setup_in_progress_;
 
   const sync_driver::SyncPrefs* sync_prefs_;
 
-  const ProfileOAuth2TokenService* token_service_;
-
-  const SigninManagerWrapper* signin_;
+  // A function that can be invoked repeatedly to determine whether sync can be
+  // started. |start_backend_| should not be invoked unless this returns true.
+  base::Callback<bool()> can_start_;
 
   // The callback we invoke when it's time to call expensive
   // startup routines for the sync backend.
   base::Closure start_backend_;
 
   // The time at which we invoked the start_backend_ callback.
   base::Time start_backend_time_;
 
   base::TimeDelta fallback_timeout_;
 
   // Used to compute preferred_types from SyncPrefs as-needed.
   syncer::ModelTypeSet registered_types_;
 
   base::WeakPtrFactory<StartupController> weak_factory_;
 };
 
 }  // namespace browser_sync
 
 #endif  // COMPONENTS_SYNC_DRIVER_STARTUP_CONTROLLER_H_