Revert of Implement software fallback for PPB_VideoDecoder.

Revert of Implement software fallback for PPB_VideoDecoder. (https://codereview.chromium.org/311853005/)

Reason for revert:
Broke blink Linux tests compile.http://build.chromium.org/p/chromium.webkit/builders/Linux%20Tests/builds/37259

Original issue's description:
> Implement software fallback for PPB_VideoDecoder.
> This modifies the proxy to implement software fallback mode.
> The main change is to the host, which now can work with
> media::VideoDecoders.
> 
> media::VideoDecoder works differently from media::VideoDecodeAccelerator
> so an adapter object, content::VideoDecoderShim is defined. It lives on the main thread and drives the actual decoder on the media thread via a child DecoderImpl class, which sends back frames of video. VideoDecoderShim receives those and converts frames to GL textures.
> 
> gpu::Mailboxes are used so the host can create textures that are aliased
> to the plugin's textures.
> 
> The test plugin has been changed to include bitstream data for VP8 in order to
> test the software decoder. The data is in ppapi/examples/video_decode/testdata.h
> alongside the H264 data. The file diff is too large for this site but is structured
> something like this:
> 
> const unsigned char kData[] = {
> #if defined USE_VP8_TESTDATA_INSTEAD_OF_H264
> ...  lots of VP8 data
> 
> #else  // !USE_VP8_TESTDATA_INSTEAD_OF_H264
> ...  lots of H264 data
> 
> #endif  // USE_VP8_TESTDATA_INSTEAD_OF_H264
> };
> 
> 
> There is a TODO to convert the example to load a file. I'm not sure how to go
> about that but am willing to do the work if someone can point the way.
> 
> BUG=281689
> R=dmichael@chromium.org, fischman@chromium.org, sievers@chromium.org, tsepez@chromium.org
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=277012

TBR=dmichael@chromium.org,fischman@chromium.org,igorc@chromium.org,piman@chromium.org,sievers@chromium.org,tsepez@chromium.org,bbudge@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=281689
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=277015

[Stephen Chennney, 2014-06-13 14:33:41]

Created Revert of Implement software fallback for PPB_VideoDecoder.

[commit-bot: I haz the power, 2014-06-13 14:34:18]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/schenney@chromium.org/337683002/1

[bbudge-google, 2014-06-13 14:34:50]

The CQ bit was unchecked by bbudge@google.com

[commit-bot: I haz the power, 2014-06-13 14:35:24]

Change committed as 277015

[bbudge-google, 2014-06-13 14:35:51]

On 2014/06/13 14:34:18, I haz the power (commit-bot) wrote:
> CQ is trying da patch. Follow status at
>  https://chromium-status.appspot.com/cq/schenney@chromium.org/337683002/1

A fix for the build break has already landed. This revert doesn't contain the
file that caused the break (ppapi/examples/video_decode/testdata.h) because it's
too big to upload.

[Stephen Chennney, 2014-06-13 14:57:37]

A revert of this CL has been created in
https://codereview.chromium.org/333903002/ by schenney@chromium.org.

The reason for reverting is: Revert of revert, which apparently wasn't a full
revert..