What possible connection might it have with anything in the past or the future ?Orwell creates an element of suspense when the smell of chocolate...

The larger implication of the memory is that it is the one
element of consciousness that lies outside of the reach of Big Brother.  Winston's
memory of something that is "moving vaguely around the edge of his consciousness," is
one that exists without the approval or sanction of the external government.  This is
significant because it proves to a great extent that while Big Brother does control
every other aspect of consciousness in Oceania, there are some experiences in the
internal, in the subjective realm, that lie outside the control of the government.  As
this idea is present, the second half of the statement is even more jarring.  The idea
of possessing "some action which he would have liked to undo, but could not," reflects
how Orwell is going to categorize resistance and the attempts of freedom in the setting
of Oceania.  Winston is seeking to rebel against Oceania, but, such attempts are gong to
be futile. The results of both of these visions are that there can be no totality
experienced by either the external or the subjective.