[Sync] Migrate SyncInternalsMessageHandler off CallJavascriptFunctionUnsafe.

components/sync/driver/fake_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_FAKE_SYNC_SERVICE_H_
 #define COMPONENTS_SYNC_DRIVER_FAKE_SYNC_SERVICE_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 65 matching lines @@
   const GURL& sync_service_url() const override;
   std::string unrecoverable_error_message() const override;
   tracked_objects::Location unrecoverable_error_location() const override;
   void AddProtocolEventObserver(ProtocolEventObserver* observer) override;
   void RemoveProtocolEventObserver(ProtocolEventObserver* observer) override;
   void AddTypeDebugInfoObserver(TypeDebugInfoObserver* observer) override;
   void RemoveTypeDebugInfoObserver(TypeDebugInfoObserver* observer) override;
   base::WeakPtr<JsController> GetJsController() override;
   void GetAllNodes(const base::Callback<void(std::unique_ptr<base::ListValue>)>&
                        callback) override;
+  SigninManagerBase* signin() const override;
 
   // DataTypeEncryptionHandler:
   bool IsPassphraseRequired() const override;
   ModelTypeSet GetEncryptedDataTypes() const override;
 
   GoogleServiceAuthError error_;
   GURL sync_service_url_;
   std::string unrecoverable_error_message_;
   std::unique_ptr<UserShare> user_share_;
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_DRIVER_FAKE_SYNC_SERVICE_H_