Use multiple RemoteFileSyncService depends on origin

Lazily instantiate and use v2 RemoteFileSyncService if V2 is enabled
only for the origin.

BUG=324215
TEST=none
NOTRY=true

Review URL: https://codereview.chromium.org/96253002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237896 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237896