Fix incorrect Rec601 YUV conversion matrix coefficient.

Fix incorrect Rec601 YUV conversion matrix coefficient.

For future reference, the rec 601 matrix can be defined by the concatenation of these 2 matrices:

[1.164  0.0    1.596 0.0]
[1.164 -0.391 -0.813 0.0]
[1.164  2.018  0.0   0.0]
[1.164  0.0    0.0   1.0]
See: http://www.fourcc.org/fccyvrgb.php

and

[1.0  0.0  0.0  -0.0625]
[0.0  1.0  0.0  -0.5   ]
[0.0  0.0  1.0  -0.5   ]
[0.0  0.0  0.0   1.0   ]
Which transforms Y by -0.0625 (-16/256) and U and V by
-0.5 (-128/256) each.

Giving us the final matrix:

[1.164  0.0    1.596  -0.87075]
[1.164 -0.391 -0.813   0.52925]
[1.164  2.018  0.0    -1.08175]
[0.0    0.0    0.0     1.0    ]

Which produces our output [R,G,B,A], when multiplied
with an input [Y,U,V,A].

Committed: https://skia.googlesource.com/skia/+/223ba624b70ed5732688e3a8a63a423a9f9b02ad

[rileya (GONE FROM CHROMIUM), 2014-09-16 04:23:11]

rileya@chromium.org changed reviewers:
+ bsalomon@google.com

[rileya (GONE FROM CHROMIUM), 2014-09-16 04:23:12]

Whoops, good thing I forgot to remove the yuv_to_rgb_effect tests from the
ignored gm list... time for some more rebaselining!

[bsalomon, 2014-09-16 13:15:53]

The CQ bit was checked by bsalomon@google.com

[bsalomon, 2014-09-16 13:15:54]

lgtm

[commit-bot: I haz the power, 2014-09-16 13:16:17]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/545983006/20001

[commit-bot: I haz the power, 2014-09-16 13:23:53]

Committed patchset #2 (id:20001) as 223ba624b70ed5732688e3a8a63a423a9f9b02ad