Implementing stereo support for G.722

This CL implements stereo support for G.722 through a new class
AudioDecoderG722Stereo derived from AudioDecoderG722.

Also implementing tests for G.722 stereo.

Review URL: https://webrtc-codereview.appspot.com/1073006

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@3452 4adac7df-926f-26a2-2b94-8c16560cd09d
4 files changed