Make toolbar overlap with contents in Preview Mode

Toolbar in Preview mode overlaps with contents of the image or video.

Changed the layout of Picker Activity to FrameLayout. In Non-Preview
mode, we add a padding to the fragment container so that toolbar doesn't
overlap with contents of the fragment.

Bug: 185801129
Test: Manual, videos attached to the bug
Change-Id: I1980f082a53dde7e5018e1917d5326d4bb3b32db
Merged-In: I1980f082a53dde7e5018e1917d5326d4bb3b32db
(cherry picked from commit dcec43535a6366bf6e0fdbe0dd952b4bacfe9a71)
2 files changed