Add recording capability to AudioManager, and implemented on windows using the WaveIn APIs.

Implementation for other platforms will follow in future patches.
Also includes a unit test.
BUG=none
TEST=no user visible change yet, just adding audio recording backend.

Review URL: http://codereview.chromium.org/2966005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@52292 0039d316-1c4b-4281-b951-d872f2087c98