Add extra key for call attributes.

Add an extra key used internally with call attributes when setting up a
call.

Test: Manual testing.
Bug: 277232336
Merged-In: Ic8b5d57df88cf9c1d8a82a11ad4934ed4ef5fd78
Change-Id: Ic8b5d57df88cf9c1d8a82a11ad4934ed4ef5fd78
1 file changed