Relanding 1143663007: VideoFrame: Separate Pixel Format from Storage Type.

Relanding 1143663007: VideoFrame: Separate Pixel Format from Storage Type.

Relanding after revert 1161803003.

(original list of reviewers:)
TBR=reveman@chromium.org, watk@chromium.org, jfroy@chromium.org, svitkine@chromium.org, DaleCurtis@chromium.org, miu@chromium.org, bbudge@chromium.org (for pepper)

Original CL description:
-----------------------------------------------------------
 VideoFrame: Segregate Pixel Format and Storage Type.

VideoFrame::Format is a mix of textures and cpu-backed
formats. Textures are then further specified by
a texture format VideoFrame::TextureFormat.

This CL consolidates this into a single pixel format
and a storage type. This applies to HOLE as well,
which is understood as another Storage type.

VideoFrame ctor forces to pass a |mailbox_holders_|
also for non-texture based formats. Another private
ctor is added without this necessity, and all the
necessary factory methods are updated.

UMA-wise: Removing NATIVE_TEXTURE and HOLE from pixel
format prevents them from being UMA-accounted, but
there are no registered instances of those anyway.

NV12 format is restricted to OS_MACOSX.

BUG=489744
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Committed: https://crrev.com/80f289fe303323361d07c5b58b23f8499903a154
Cr-Commit-Position: refs/heads/master@{#332000}

Committed: https://crrev.com/f1236fc25c67ceb18942ffc1696f24fd05e15453
Cr-Commit-Position: refs/heads/master@{#332065}

[mcasas, 2015-05-29 19:21:36]

mcasas@chromium.org changed reviewers:
- bbudge@chromium.org for pepper/ since the change

[mcasas, 2015-05-29 21:01:45]

The CQ bit was checked by mcasas@chromium.org

[commit-bot: I haz the power, 2015-05-29 21:03:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1154153003/20001

[commit-bot: I haz the power, 2015-05-29 22:39:10]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-05-29 22:39:59]

Patchset 2 (id:??) landed as
https://crrev.com/f1236fc25c67ceb18942ffc1696f24fd05e15453
Cr-Commit-Position: refs/heads/master@{#332065}

[miu, 2015-05-29 22:42:30]

Well, this solves the debate we had over having the NV12 format.  ;-)

[miu, 2015-05-29 22:42:38]

miu@chromium.org changed reviewers:
+ miu@chromium.org

[miu, 2015-05-29 22:42:39]

lgtm