Remove a superfluous DCHECK() in DownloadRateMonitor::Start()

BUG=104827
TBR=vrk

Review URL: http://codereview.chromium.org/8472004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@110903 0039d316-1c4b-4281-b951-d872f2087c98

media/base/download_rate_monitor.cc

@@ -74,7 +74,6 @@ DownloadRateMonitor::DownloadRateMonitor() {
 
 void DownloadRateMonitor::Start(
     const base::Closure& canplaythrough_cb, int media_bitrate) {
-  DCHECK(stopped_);
   canplaythrough_cb_ = canplaythrough_cb;
   stopped_ = false;
   bitrate_ = media_bitrate;