DO NOT MERGE - Fix software video decoder buffer size calculation

Various software video decoders would specify the buffer size as if it were
fully cropped, which then failed a sanity check in SoftwareRenderer.
They now return the full buffer size.

Bug: 21717327
Bug: 21443020
Change-Id: I19fcd091827ebd52a95a5509281a07ccc156e0e5
(cherry picked from commit 3ecc9db4)