Replace more ObserverList with base::ObserverList.

sync/internal_api/public/test/fake_sync_manager.h

 // Copyright (c) 2012 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 SYNC_INTERNAL_API_PUBLIC_TEST_FAKE_SYNC_MANAGER_H_
 #define SYNC_INTERNAL_API_PUBLIC_TEST_FAKE_SYNC_MANAGER_H_
 
 #include <string>
 
 #include "base/memory/ref_counted.h"
@@ skipping 101 matching lines @@
       syncer::TypeDebugInfoObserver* observer) override;
   void UnregisterDirectoryTypeDebugInfoObserver(
       syncer::TypeDebugInfoObserver* observer) override;
   bool HasDirectoryTypeDebugInfoObserver(
       syncer::TypeDebugInfoObserver* observer) override;
   void RequestEmitDebugInfo() override;
 
  private:
   scoped_refptr<base::SequencedTaskRunner> sync_task_runner_;
 
-  ObserverList<SyncManager::Observer> observers_;
+  base::ObserverList<SyncManager::Observer> observers_;
 
   // Faked directory state.
   ModelTypeSet initial_sync_ended_types_;
   ModelTypeSet progress_marker_types_;
 
   // Test specific state.
   // The types that should fail configuration attempts. These types will not
   // have their progress markers or initial_sync_ended bits set.
   ModelTypeSet configure_fail_types_;
   // The set of types that have been cleaned up.
@@ skipping 14 matching lines @@
   TestUserShare test_user_share_;
 
   NullSyncContextProxy null_sync_context_proxy_;
 
   DISALLOW_COPY_AND_ASSIGN(FakeSyncManager);
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_INTERNAL_API_PUBLIC_TEST_FAKE_SYNC_MANAGER_H_