Revert "Temporarily disable HWA decoding support."

This reverts commit e8ee3471a56a1c23e86687d9d90e59564c7ffb44.
Fixed the compile error

BUG-240

the ozone/media uses mesa header GL/gl.h. However, video.gypi didn't add it
in the include_dirs. So, that will result in 'fatal error: GL/gl.h: No such
file or directory'. Meanwhile, it will fix BUG-240
Temporarily remove ozone dependency for gl

The old implementation will result that the third party window system can't depend on ui/gl
because of cycling dependency. So temporarily remove ozone dependency for gl.

BUG=240
Merge pull request #253 from qjia7/open_vda

Enable HWA decoding support