Revert 254749 "[AudioPlayer] Don't start a playback automaticall..."

There have been failures in related tests. Oddly they don't correspond to the CL
range, but started later, but see:

http://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20Tests%20%282%29/builds/22021

> [AudioPlayer] Don't start a playback automatically when reopening
> 
> BUG=chrome-os-partner:26171
> TEST=manually
> 
> Review URL: https://codereview.chromium.org/181063007

TBR=yoshiki@chromium.org

Review URL: https://codereview.chromium.org/182383014

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254779 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 254779