Merge pull request #11221 from huchengtw-moz/video/Bug_898993_thumbnail_size_is_not_compitable_to_hdpi

Bug 898993 - the creation of thumbnail size is not compatible to hdpi de...(cherry picked from commit 49b1f68b0e2152557bb7c2defb2a5f9d7a0648c6)

Conflicts:
	apps/video/js/video.js
Merge pull request #13003 from huchengtw-moz/video/Bug_898993-v1.1.0hd

cherry-pick from master
Merge pull request #11221 from huchengtw-moz/video/Bug_898993_thumbnail_...