Remember just the other day when Facebook removed the “Clear Chat History” button? Well, the outcry was loud enough that Facebook has announced that the feature will be restored. Users will have access to the option to clear their chat history at the top of the scroll area. This placement is not dramatically different from its original location.
Facebook even offered an explanation of their decision making process. According to the statement, "Based on the tests, we’ve decided to keep the ‘clear chat history’ link and to optimize it’s placement within the Chat interface. Given its low usage, we are placing it at the top of the Chat scroll ― where it is still easily accessible without cluttering UI space throughout the course of the chat."
Basically, Facebook backpedaled after the negative reaction. One has to wonder why they thought they could get away with it in the first place. People say things in chat sessions that they'd rather not have a record of.