“）]}'`在Google api响应中是什么意思

Question

我检查了google.com的网络请求，发现其json apis返回以）]}'开头的json字符串，有人可以告诉我）]}'的意思吗？

以下是原始响应：

)]}' [[["\u003cb\u003egcp\u003c\/b\u003e",35,[39],{"du":"/complete/deleteitems?client\u003dpsy-ab\u0026delq\u003dgcp\u0026deltok\u003dAKtL3uSL5Crj5-LO29MAz1misN0Ai-fB2A","zf":27}],["\u003cb\u003egoogle \u0026#39;)]}\u0026#39;\u0026#39;\u003c\/b\u003e",35,[39],{"du":"/complete/deleteitems?client\u003dpsy-ab\u0026delq\u003dgoogle+\u0027)%5D%7D\u0027\u0027\u0026deltok\u003dAKtL3uSrYkbA86jTixBUjBbbbcFs6mn03A","zf":27}],["\u003cb\u003egoogle json \u0026#39;)]}\u0026#39;\u0026#39;\u003c\/b\u003e",35,[39],{"du":"/complete/deleteitems?client\u003dpsy-ab\u0026delq\u003dgoogle+json+\u0027)%5D%7D\u0027\u0027\u0026deltok\u003dAKtL3uSVVozYne6-j84rWSFP3C02eJefgg","zf":27}],["\u003cb\u003egoogle api )]}\u0026#39;\u003c\/b\u003e",35,[39],{"du":"/complete/deleteitems?client\u003dpsy-ab\u0026delq\u003dgoogle+api+)%5D%7D\u0027\u0026deltok\u003dAKtL3uRezsyZ771Tg7jjXAsqDMoVWEYbhQ","zf":27}],["\u003cb\u003ecollection.find option [fields] is deprecated and will be removed in a later version\u003c\/b\u003e",35,[39],{"du":"/complete/deleteitems?client\u003dpsy-ab\u0026delq\u003dcollection.find+option+%5Bfields%5D+is+deprecated+and+will+be+removed+in+a+later+version\u0026deltok\u003dAKtL3uTPgRKuEEOJAa5KYD8cjc1aSGMpeQ","zf":27}],["\u003cb\u003esimple discovery properties\u003c\/b\u003e",35,[39],{"du":"/complete/deleteitems?client\u003dpsy-ab\u0026delq\u003dsimple+discovery+properties\u0026deltok\u003dAKtL3uRmN7zw0WEaydYvYqys8bpZCZhqfA","zf":27}]],{"q":"d5sEt_KHwsqs1ovxLyGrt3W8in8"}]

我猜想是因为content-coding: br，但不确定。