Fix N7 camera aspect ratio.

N7 video preview generates stretched output:
https://code.google.com/p/android/issues/detail?id=70830.
To workaround the problem set camera picture size in
addition to video preview size with the same resolution.

BUG=3971
R=braveyao@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/25009004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7581 4adac7df-926f-26a2-2b94-8c16560cd09d