[Sync] Cleanup all tab sync enabling logic now that its on by default.

BUG=none
TEST=


Review URL: https://chromiumcodereview.appspot.com/10443046

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@139462 0039d316-1c4b-4281-b951-d872f2087c98
  static NudgeDelayStrategy GetNudgeDelayStrategy(const ModelType& type) {
    switch (type) {
     case syncable::AUTOFILL:
       return ACCOMPANY_ONLY;
     case syncable::PREFERENCES:
     case syncable::SESSIONS:
       return CUSTOM;
     default:
       return IMMEDIATE;
    }
  }

  static NudgeDelayStrategy GetNudgeDelayStrategy(const ModelType& type) {
    switch (type) {
     case syncable::AUTOFILL:
       return ACCOMPANY_ONLY;
     case syncable::PREFERENCES:
     case syncable::SESSIONS:
       return CUSTOM;
     default:
       return IMMEDIATE;
    }
  }
