Implement WebKitClientImpl::loadAudioResource() to decode in-memory audio file data for use by WebKit.
Most of the interesting low-level code is being added in the media directory.

BUG=NONE
TEST=NONE (tested locally with web audio API loading files of format .wav .aif .mp3 .m4a 16bit 24bit
In the longer term, WebKit layout tests will comprehensively exercise this code)

Review URL: http://codereview.chromium.org/5880002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@69458 0039d316-1c4b-4281-b951-d872f2087c98