Rewrite AudioRendererHost to use AudioController

      This change will move all the audio device methods calls to
AudioController so we can move all the audio related methods calls off the IO
thread. This change will let AudioRendererHost to use the AudioController API.
This involves rewriting the whole AudioRendererHost.

After this patch we can implement proper pause operations that is only possible
if they are hosted on a separated thread due to their blocking nature.

Normal latency mode is fully covered by unit tests, including audio control
operations and data conversation.

Low latency mode using SyncSocket is tested only for stream creation and still
need to handle cases during shutdown when we want SyncSocket to return
immediately.

TEST=unit_tests --gtest_filter=AudioRendererTest.*
BUG=39885

Review URL: http://codereview.chromium.org/2850016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@51743 0039d316-1c4b-4281-b951-d872f2087c98