Fix an issue that page will enter fullscreen when exiting fullscreen video

SetVideoSurface() can be called with an empty surface, instead of a fullscreen surface.

BUG=352211, 355960

Review URL: https://codereview.chromium.org/211823003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@259482 0039d316-1c4b-4281-b951-d872f2087c98
1 file changed