Have MutableProfileOAuth2TokenService get TokenWebData from SigninClient

This CL starts the process of eliminating PO2TS's direct knowledge of Profile.
It makes the following changes:
- Adds a method to SigninClient to return the TokenWebData to use
- Augments PO2TS::Initialize() to take in a SigninClient to use
- Changes MO2TS to get the TokenWebData from the SigninClient rather than the
  Profile
- [cleanup] Eliminates an unused method from the SigninClient interface

BUG=334184
R=rogerta@chromium.org

Review URL: https://codereview.chromium.org/192323008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256184 0039d316-1c4b-4281-b951-d872f2087c98
[StorageMonitor] Move name generation to StorageInfo.

BUG=261350

Review URL: https://codereview.chromium.org/120303003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256185 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 256185