[AudioPlayer] Enable new audio-player by default

This patch is reland of r248758, disabling the flaky tests.

BUG=273308
TEST=manually tested
TBR=hirono@chromium.org

Review URL: https://codereview.chromium.org/155723003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249031 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249031
Add a11y on-screen keyboard to accessibility menu on system tray.

BUG=340760

Review URL: https://codereview.chromium.org/137993021

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249033 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249033