Escaping from Google chat
Exporting your Google Talk/Gmail chat logs is available by enabling IMAP export of your Gmail account and choosing the label “Chats” to be included in IMAP.
Note that these chats are different from the ones provided by the Hangouts product. Once you have used any Hangouts product (e.g. a mobile app, inside Gmail or inside Google+), your chats are available via the instructions on the Hangouts page. Reverting Hangouts to the old chat in Gmail does not affect this.