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