[Sync] Add keystore encryption info to about:sync

This patch adds the following fields under the encryption section of about:sync
- Has Keystore Key: whether the encryption handler has a keystore encryption key
- Migration Time: the time migration was performed, or "Not Migrated" if
  migration hasn't been performed yet
- Passphrase Type: the actual passphrase type (provides more detail than
   Is Using Explicit Passphrase, but stored at a diff layer)

Added sync/api/time.h, which just includes sync/util/time.h but is accessible
from chrome/

BUG=129665


Review URL: https://chromiumcodereview.appspot.com/10917246

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@157499 0039d316-1c4b-4281-b951-d872f2087c98
13 files changed