Checks for low storage in wide-angle pano mode.

1. Storage.LOW_STORAGE_THRESHOLD -> Storage.LOW_STORAGE_THRESHOLD_BYTE.
2. Checks for low storage before start preview in wide-angle pano mode.
3. Add low storage warning message for debugging when in wide-angle pano mode.

  bug:10691367

Change-Id: Iffd96d322b33591c8f235fcf5680e86cf0f06571
5 files changed