Fix PPIXEL_FORMAT_NV21 returned string

Fix PPIXEL_FORMAT_NV21 returned string

BUG=436651
In the case of PIXEL_FORMAT_NV21, the PixelFormatToString()
function will return "YV12". This cl modify it to "NV21"

Committed: https://crrev.com/f70d7d4bbce8652375235dab1f5434f6faa5e23f
Cr-Commit-Position: refs/heads/master@{#305742}

[zhaoze.zhou, 2014-11-25 19:44:42]

zhaoze.zhou@partner.samsung.com changed reviewers:
+ lionel.g.landwerlin@intel.com

[zhaoze.zhou, 2014-11-25 19:45:53]

zhaoze.zhou@partner.samsung.com changed reviewers:
+ vrk@chromium.org

[zhaoze.zhou, 2014-11-25 19:45:54]

vrk@chromium.org: Can you take a look? I am not sure the
returned value is done by purpose or by mistake. Thanks

[mcasas, 2014-11-25 21:18:50]

On 2014/11/25 19:45:54, zhaoze.zhou wrote:
> mailto:vrk@chromium.org: Can you take a look? I am not sure the
> returned value is done by purpose or by mistake. Thanks

Tip: Ping magjed@ for review and tommi@ or perkj@ for Owners RS.

[zhaoze.zhou, 2014-11-25 21:23:59]

zhaoze.zhou@partner.samsung.com changed reviewers:
+ magjed@chromium.org, perkj@chromium.org, tommi@chromium.org

[zhaoze.zhou, 2014-11-25 21:24:21]

On 2014/11/25 21:18:50, mcasas wrote:
> On 2014/11/25 19:45:54, zhaoze.zhou wrote:
> > mailto:vrk@chromium.org: Can you take a look? I am not sure the
> > returned value is done by purpose or by mistake. Thanks
> 
> Tip: Ping magjed@ for review and tommi@ or perkj@ for Owners RS.

OK..Thanks. :)

[vrk (LEFT CHROMIUM), 2014-11-25 22:48:01]

Nit: looks like the bug is obvious, but could you add a BUG= link?

[vrk (LEFT CHROMIUM), 2014-11-25 22:48:30]

Oops, didn't realize this was closed.

[zhaoze.zhou, 2014-11-25 22:52:35]

On 2014/11/25 22:48:30, vrk wrote:
> Oops, didn't realize this was closed.

https://codereview.chromium.org/416553002 This is the original cl that add it
this returned string. seems there's no bug link for it.

[vrk (LEFT CHROMIUM), 2014-11-25 23:04:02]

Haha, that's my mistake. I shouldn't have LG'd  CL 416553002 since it doesn't
have a BUG= link :)

Please create a bug for this CL at crbug.com if it doesn't already exist.

[zhaoze.zhou, 2014-11-25 23:34:22]

On 2014/11/25 23:04:02, vrk wrote:
> Haha, that's my mistake. I shouldn't have LG'd  CL 416553002 since it doesn't
> have a BUG= link :)
> 
> Please create a bug for this CL at http://crbug.com if it doesn't already
exist.

Done. :)

[vrk (LEFT CHROMIUM), 2014-11-25 23:35:43]

The CQ bit was checked by vrk@chromium.org

[vrk (LEFT CHROMIUM), 2014-11-25 23:35:44]

lgtm

[commit-bot: I haz the power, 2014-11-25 23:36:39]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/762513002/1

[commit-bot: I haz the power, 2014-11-26 00:51:55]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-11-26 00:53:10]

Patchset 1 (id:??) landed as
https://crrev.com/f70d7d4bbce8652375235dab1f5434f6faa5e23f
Cr-Commit-Position: refs/heads/master@{#305742}