Dark Gallery [TRDS]

Change-Id: I632b252280118f61f356f4a6dae1039e02b82241
Camera: Ensure background edition complete on back Key

Block back key event till the image will get displayed
while user pressed edit option/icon. This'll allow the
background process to cleanup memory. Added null check
and bitmap recycle to avoid crash.

Change-Id: Ied1c1f3ecf07a352743908135a5b7976373a58a3
CRs-Fixed:  587402