Broadcast an intent after turning off Grayscale

Settings will send a broadcast when the user disable Grayscale in
Settings. Also, Settings registers a broadcast receiver to monitor the
status changed of Grayscale.

Bug: 118387886
Test: robotests
Change-Id: I92d1b9adf7a600b4abac943ebbd5a11d02d3d1b8
2 files changed