FTrackEditorThumbnailCache ( const [TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< [FTrackEditorThumbnailPool](API\Editor\MovieSceneTools\TrackEditorThumbnail\FTrackEditorThumbnailPool) > & ThumbnailPool, [IViewportThumbnailClient](API\Editor\MovieSceneTools\TrackEditorThumbnail\IViewportThumbnailClient) * InViewportThumbnailClient )