Share only 360-degree panoramas with new MIME type

Bug: 7302972

Instead of using the UsePanoramaViewer attribute in XMP metadata,
ensure that the panorama is full 360 degree by checking if the
cropped width is same as the full panorama width.

Change-Id: I66d864df96052f96db5fa19fb02b3abe214b4dec
9 files changed