function didWrite(chunk, fileSize)
        {
            if (fileSize === -1)
                return;
            if (chunk) {
                chunk.startOffset = this._fileSize;
                chunk.endOffset = fileSize;
                chunk.string = null;
            }
            this._fileSize = fileSize;
        }
@this {WebInspector.TempFileBackingStorage}
@param {?WebInspector.TempFileBackingStorage.Chunk} chunk
@param {number} fileSize