Add accelerated video decoder interface, VP8 and H.264 implementations and hook up to V4L2SVDA

Reland: Add accelerated video decoder interface, VP8 and H.264 implementations and hook up to V4L2SVDA.

This is a reland as the previous CL has an issue with BUILD.gn and failed gn build.

An AcceleratedVideoDecoder is a video decoder that requires support from an
external accelerator (typically a hardware accelerator) to partially
offload the decode process after parsing stream headers, and performing
reference frame and state management.

In this design, the hardware-independent decoder implementation interfaces
with a HW-specific Accelerator to offload last stages of the decode process.

Add the interface for AcceleratedVideoDecoder, decoders for VP8 and H264,
V4L2-specific Accelerators for VP8 and H264 and a common accelerator/client
class for V4L2.

TEST=vdatest VP8/H264, mp4 local video playback, apprtc decode
BUG=chrome-os-partner:33728
TBR=wuchengli@chromium.org,kcwu@chromium.org,owenlin@chromium.org,xhwang@chromium.org,scherkus@chromium.org,dalecurtis@chromium.org

Committed: https://crrev.com/3c09b9b26ee6fc8b43c7535070cfa08aba1285cf
Cr-Commit-Position: refs/heads/master@{#311464}

[Pawel Osciak, 2015-01-14 11:13:55]

posciak@chromium.org changed reviewers:
+ dalecurtis@chromium.org, kcwu@chromium.org, owenlin@chromium.org,
scherkus@chromium.org, wuchengli@chromium.org, xhwang@chromium.org

[Pawel Osciak, 2015-01-14 11:26:25]

Patchset #1 (id:1) has been deleted

[Pawel Osciak, 2015-01-14 12:46:46]

The CQ bit was checked by posciak@chromium.org

[commit-bot: I haz the power, 2015-01-14 12:47:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/813693006/20001

[commit-bot: I haz the power, 2015-01-14 12:58:41]

Committed patchset #1 (id:20001)

[commit-bot: I haz the power, 2015-01-14 12:59:31]

Patchset 1 (id:??) landed as
https://crrev.com/3c09b9b26ee6fc8b43c7535070cfa08aba1285cf
Cr-Commit-Position: refs/heads/master@{#311464}

[Ken Rockot(use gerrit already), 2015-01-14 22:34:16]

A revert of this CL (patchset #1 id:20001) has been created in
https://codereview.chromium.org/852103002/ by rockot@chromium.org.

The reason for reverting is: This is breaking arm builds. See for example:

https://build.chromium.org/p/chromiumos.chromium/builders/Daisy%20%28chromium....