Add additional overriding methods to signature files

This change adds overriding methods that are essential to compile the
stubs generated from the signature files.

More information and the background for this change is available at
go/add-overriding-one-pager.

Test: m checkapi
Change-Id: Ifc1876eb60a4b716f72c86003dc9bea0081e9a4c
20 files changed