Squashed commit of the following:

commit cb11364feefc200f10af6a01f776803acba2792a
Author: Andreas Huber <andih@google.com>
Date:   Thu Jan 14 14:05:36 2010 -0800

    Even if the decoder didn't extract the thumbnail at the specified time, accept it for now.

commit a54c0244b305caf11e67db49b7d3d8dba5f77751
Author: Andreas Huber <andih@google.com>
Date:   Thu Jan 14 11:37:15 2010 -0800

    Add some checks to make sure we extract the correct thumbnail frame, also revert to the hardware decoders for thumnbail extraction if the software decoders failed.