ChromeOS: Remove unused IBus classes from chromeos/.

BUG=171351
R=nona@chromium.org, satorux@chromium.org

Review URL: https://codereview.chromium.org/50243005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233276 0039d316-1c4b-4281-b951-d872f2087c98
signin: record http response codes and net errors in OAuth2AccessTokenFetcher.

I also changed the token fetcher to return SERVICE_ERROR when
we see an HTTP 400 + custom service error, versus INVALID_GAIA_CREDENTIALS.

R=courage@chromium.org, droger@chromium.org, pavely@chromium.org, rlarocque@chromium.org
TBR=rlarocque@chromium.org
(/invalidation)

BUG=314705

Review URL: https://codereview.chromium.org/57993006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233277 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 233277