Additional OAuth2 tests for ChromeOS
- authentication attempt for invalid OAuth2 refresh token
- authentication of an existing user  

BUG=none
TEST=OAuth2.*

Review URL: https://codereview.chromium.org/108663008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241581 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241581
sync: make sessions sync v2 work

Summary of work:
- get tests passing with or without --enable-sync-sessions-v2 (unit_tests, browser_tests, sync_integration_tests)
- did not deal with the disabled sessions perf test. requires non-trival changes, and I'm not sure it's worthwhile yet.
- impelement StopSyncing, GetAllSyncData
- fixed a bug discovered by manual testing where the client tag for a tab node was using an invalid tab_node_id on update.
- remove most remaining references to SessionModelAssociator
- ran some manual coverage of backwards compatibility with v1

This patch does add temporary complexity to a few tests, namely WrenchMenuControllerTest and RecentTabsSubMenuModelTest. The goal was to make things work with or without the flag to minimize diffs during rollout, if we have to swap flag values. I'll remove the extra code once SessionModelAssociator is no more.

BUG=98892

Review URL: https://codereview.chromium.org/110583002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241582 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241582