Revert 152221 - chromeos: Sync animation.

Revert 152221 - chromeos: Sync animation.
This was causing Linux ChromiumOS (dbg) browser_tests to fail with timeouts on several tests, identified with a local bisect.

- Pulse app list button while LauncherModel has STATUS_LOADING;
- Remove LauncherItemStatus::STATUS_IS_PENDING etc since it is no longer needed;
- ChromeLauncherController sets LauncherModel::STATUS_LOADING on starting and
  watch for sync finish and pending extension install. It sets
  LauncherModel::STATUS_NORMAL when sync is finished and there is no pending
  extension install from sync, or when a maximum 60 seconds timeout since
  turning on loading status;

BUG=129236
TEST=Verify sync animation after OOBE.

Review URL: https://chromiumcodereview.appspot.com/10829268

TBR=xiyuan@chromium.org
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=152352