Update FFmpegDemuxer unknown duration logic to work for video-only streams.

The FFmpegDemuxer would only compute the duration at the end of
playback for clips without a duration that contained audio. This was not
being done for video-only streams which resulted inconsistent behavior.
This change simply make the duration computation logic apply to all
stream types.

TEST=FFmpegDemuxerTest.Read_EndOfStream_NoDuration_VideoOnly, FFmpegDemuxerTest.Read_EndOfStream_NoDuration_AudioOnly

Review URL: https://codereview.chromium.org/105503011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243304 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 243304
Revert 242767 "Add a renderer side version of the referrer check..."

> Add a renderer side version of the referrer check in the net library
> 
> This should hopefully give us enough information to debug the issue
> 
> BUG=331097
> R=battre@chromium.org
> 
> Review URL: https://codereview.chromium.org/105853004

TBR=jochen@chromium.org

Review URL: https://codereview.chromium.org/93803005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243305 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 243305