Removing MockOAuth2TokenService from UberauthTokenFetcher

(This is part of removing virtual keyword from O2TS.StartRequest)

Dependent on https://codereview.chromium.org/23382008/

BUG=282454

Review URL: https://chromiumcodereview.appspot.com/24291002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@224671 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 224671
UMA for OSX App Launcher daily usage, borrowed from Win.

BUG=274058
TEST=None

Review URL: https://chromiumcodereview.appspot.com/24303004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@224672 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 224672