Switch audio synchronization from sleep() based to select() based.

Uses select() to efficiently wait for data from the renderer with a
timeout instead of using sleep() or always assuming the renderer
is ready.

Fixes glitching and / or CPU hogging when the renderer isn't ready.

BUG=179058, 180841, 260772, 269672, 
TEST=Swap from 44kHz to 16kHz html5 playback, ensure glitch free.

Review URL: https://codereview.chromium.org/22886005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230515 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 230515