DO NOT MERGE: Add cec message handler to hdmi cec jni implementation

Notification for incoming cec message can be issued
from any thread but jni can call java method
in the thread that jni knows like service thread.
So this change delegates incoming message to
jni-friendly thread, service thread by exploit
looper of service thread.

Change-Id: If3b141d917df3e209912af1778eb509777199969