Make CameraDataAdapter background new data loading and post to listener

To avoid potentially expensive operations in main thread, only call
back to filmstrip on the main thread. Do all processing in background.
Consistently enforce that all listener callbacks are main thread by
posting to a main thread handler.

Bug: 17437217
Change-Id: I6a96690218043cc42644d12a4162322cc2ee7e8f
2 files changed