Revert of Revert of Add compressed texture capabilities for GPU devices

Revert of Revert of Add compressed texture capabilities for GPU devices
(https://codereview.chromium.org/307543002/)

Reason for revert:
Re-landing the original CL, because the revert didn't fix things.  See http://skbug.com/2608 ('RunDecodingTests failing on multiple platforms')

Original issue's description:
> Revert of Add compressed texture capabilities for GPU devices (https://codereview.chromium.org/292323003/)
> 
> Reason for revert:
> RunDecodingTests failing on multiple platforms.  Please use trybots to validate and re-land.
> 
> Original issue's description:
> > Add compressed texture capabilities for GPU devices
> > 
> > BUG=skia:
> > 
> > Committed: http://code.google.com/p/skia/source/detail?r=14880
> > 
> > Committed: http://code.google.com/p/skia/source/detail?r=14901
> 
> TBR=bsalomon@google.com,robertphillips@google.com,krajcevski@google.com
> NOTREECHECKS=true
> NOTRY=true
> BUG=skia:
> 
> Committed: http://code.google.com/p/skia/source/detail?r=14902

TBR=bsalomon@google.com,robertphillips@google.com,krajcevski@google.com
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Committed: http://code.google.com/p/skia/source/detail?r=14903

[epoger, 2014-05-27 19:24:27]

Created Revert of Revert of Add compressed texture capabilities for GPU devices

[epoger, 2014-05-27 19:24:59]

The CQ bit was checked by epoger@google.com

[commit-bot: I haz the power, 2014-05-27 19:25:26]

CQ is trying da patch. Follow status at
 https://skia-tree-status.appspot.com/cq/epoger@google.com/302553008/1

[commit-bot: I haz the power, 2014-05-27 19:25:31]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-05-27 19:25:32]

Presubmit check for 302553008-1 failed and returned exit status 1.

Running presubmit commit checks ...

** Presubmit ERRORS **
Since the CL is editing public API, you must have an LGTM from one of:
('reed@chromium.org', 'reed@google.com', 'bsalomon@chromium.org',
'bsalomon@google.com')

Presubmit checks took 1.0s to calculate.

[epoger, 2014-05-27 19:26:24]

The CQ bit was checked by epoger@google.com

[commit-bot: I haz the power, 2014-05-27 19:26:51]

CQ is trying da patch. Follow status at
 https://skia-tree-status.appspot.com/cq/epoger@google.com/302553008/1

[commit-bot: I haz the power, 2014-05-27 19:27:04]

Change committed as 14903