[Sync] Migrate SyncInternalsMessageHandler off CallJavascriptFunctionUnsafe.

components/sync/driver/sync_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_SYNC_DRIVER_SYNC_SERVICE_H_
 #define COMPONENTS_SYNC_DRIVER_SYNC_SERVICE_H_
 
 #include <memory>
 #include <string>
 
 #include "base/callback.h"
 #include "base/location.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/time/time.h"
 #include "components/sync/base/model_type.h"
 #include "components/sync/driver/data_type_encryption_handler.h"
 #include "components/sync/driver/sync_service_observer.h"
 #include "components/sync/engine/connection_status.h"
 #include "google_apis/gaia/google_service_auth_error.h"
 
 class GoogleServiceAuthError;
+class SigninManagerBase;
 
 namespace sync_sessions {
 class OpenTabsUIDelegate;
 }  // namespace sync_sessions
 
 namespace syncer {
 
 class BaseTransaction;
 class DataTypeController;
 class JsController;
@@ skipping 307 matching lines @@
   // Asynchronously fetches base::Value representations of all sync nodes and
   // returns them to the specified callback on this thread.
   //
   // These requests can live a long time and return when you least expect it.
   // For safety, the callback should be bound to some sort of WeakPtr<> or
   // scoped_refptr<>.
   virtual void GetAllNodes(
       const base::Callback<void(std::unique_ptr<base::ListValue>)>&
           callback) = 0;
 
+  // Non-owning pointer to sign in logic that can be used to fetch information
+  // about the currently signed in user.
+  virtual SigninManagerBase* signin() const = 0;
+
  protected:
   SyncService() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SyncService);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_DRIVER_SYNC_SERVICE_H_