It's bound to the recently added command 'diff-apply-buffer'.
:help "Apply the current hunk to the source file and go to the next"]
["Test applying hunk" diff-test-hunk
:help "See whether it's possible to apply the current hunk"]
+ ["Apply all hunks" diff-apply-buffer
+ :help "Apply all hunks in the current diff buffer"]
["Apply diff with Ediff" diff-ediff-patch
:help "Call `ediff-patch-file' on the current buffer"]
["Create Change Log entries" diff-add-change-log-entries-other-window