Add constant for System actions in Sharesheet.

Test: manual; compiles
Bug: 140928181
Change-Id: I66e38efbf87bed573766a17cc1401ed19e606c48
(cherry picked from commit a2d980661cb7d02c917764bde1d426cb55bc2d88)

Merged-In: I66e38efbf87bed573766a17cc1401ed19e606c48
1 file changed