Gallery2: fix FC when try to open video folder as MMS attachment.

If there are too many videos in the folder, it will takes some
time to check if all the items are videos, then the application
may not responding.

If it is get content from other apps, it do not display option
menu, no need to check all items.

CRs-Fixed: 581769

Change-Id: Ie59830c8756e3a2ece7fcaa526d8f09212b20d6f