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
Gallery2: add support for the DASH mimetype

Add support for the DASH mimetype

CRs-Fixed: 539815
Change-Id: Ibbd03a2e4e3b1ca9224d4651e1c518e2ba51ba77