camera: changes to provide postview callback.
camera: changes to provide postview callback.

Thumbnail buffer is used for sending postview callback.

Bug: 7378257
Change-Id: I8e8db25420a1a3df5431befb9fc9b1a3cbbe7477
Signed-off-by: Iliyan Malchev <b9962a40c76f189681da2829a74a26cab77021ea@google.com>

maruos/android_device_lge_hammerhead,maruos/android_device_lge_hammerhead,maruos/android_device_lge_hammerhead,maruos/android_device_lge_hammerhead