Improve error handling and revert old debugging code.

This pulls out some of the extra debugging code I've added for the
debug builds I've been handing out.  Specifically:
- Checks error status on Start() and Stop().
- Ensures preconfigured AudioBus channel count matches
buffer list count.
- Removes old debugging code that is never triggered.

BUG=160920
TEST=none
R=scherkus@chromium.org

Review URL: https://codereview.chromium.org/56053003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232796 0039d316-1c4b-4281-b951-d872f2087c98
2 files changed