Adding executor with repeat functionality

The use case I'm looking at is for the seek bar in media controls. While
playing, the elapsed time needs to be continuously checked with a fixed
delay (ie. polling the elapsed time).

Bug: 154352658
Test: Added RepeatableExecutorTest
Change-Id: I142545e9a405c38fda6002a85fa3c47343f2fce4
4 files changed