This question is an exact duplicate of:
Can you guess how the NSA can read Facebook chats, while Facebook does use SSL encryption? Requesting information directly from the Facebook HQ is possible (see also who betrayed Facebook in favor of the NSA), but if you read the details of this program you will see that they are talking about the raw TCP packages.
"enables an analyst using XKeyscore to read the content of Facebook chats " http://www.theguardian.com/world/2013/jul/31/nsa-top-secret-program-online-data
Former Facebook security chief is now working for the NSA