[Android] Force using ContentVideoViewLegacy to make the android fullscreen video works.

Currently the default ContentVideoView in upstream is not ready for production usage. Bugs
are many about focus related. We turn to use ContentVideoViewLegacy now and when bug in
chromium is fixed, will revert the change.

BUG=https://crosswalk-project.org/jira/browse/XWALK-1608
Merge pull request #1921 from sqliu/fix-fullscreen-video

[Android] Force using ContentVideoViewLegacy to make the android fullscr...