Gallery2: update selected number for database change

mSourceMediaSet will be updated for database changed
But mTotal will not if it is more than zero.

Update mTotal all the time for database changed

CRs-Fixed: 407961

Change-Id: I432b33ba62c04b18c6a1628b6b10dc9b77a72fc1
Gallery2: set the progress bar when we pause the video

The progress bar isn't set when we pause the video.

Set the progress bar when we pause the video

CRs-Fixed: BZ1623

Change-Id: I3d450df6fdf8195983692ed8a71ab42717e9c36c
Gallery2: Fix the superposition of two images issue

When we zoom out to film mode from single photo mode with more than two
fingers, PhotoView will receive multi onScaleBegin/onScaleEnd streams.
But when mModeChanged is true, it will only notify PositionController to
beginScale but not to endScale, then mInScale remains in true state. So
when we back to single photo mode from film mode, focuse photo can't do
scale animation in Box.startSnapback().

According to the logic in onScaleEnd(), we will ignore other scale begin
notification if film mode has been changed.

CRs-Fixed: 551984

Change-Id: I468d932adab0a3540f107501db4d0ea4b7ffbb10
Gallery2: Remove slideshow option if all files of the folder are video

Enter Gallery and open folder whose files are all video, press
menu key should no slideshow option.

Add condition to remove slideshow if the folder are all video
files.

CRs-Fixed: 574984

Change-Id: Ib1603f1609b6490e44039ab64abefb44f14bd477