Revert 169101 "Android, video: clean-up WebMediaPlayerClientImpl..."

This might break many WebRtcBrowserTest on android bots, preventing us from rolling Android.

> Android, video: clean-up WebMediaPlayerClientImpl::paintOnAndroid().
> 
> Android doesn't support WebMediaPlayer::LoadTypeMediaStream so change "if
> statement" to ASSERT. See WebMediaPlayerAndroid::load().
> 
> Remove unnecessary OwnPtr<WebGraphicsContext3DProvider> object construction.
> 
> BUG=349871
> 
> Review URL: https://codereview.chromium.org/196603006

TBR=dongseong.hwang@intel.com

Review URL: https://codereview.chromium.org/196383009

git-svn-id: svn://svn.chromium.org/blink/trunk@169139 bbb929c8-8fbe-4397-9dbb-9b2b20218538