Revert of Change SkDecodingImageGenerator API

Revert of https://codereview.chromium.org/93703004/
Reason for revert: Test failures

TBR=scroggo@google.com,djsollen@google.com,reed@google.com,halcanary@google.com
NOTREECHECKS=true
NOTRY=true

Committed: http://code.google.com/p/skia/source/detail?r=12747

[robertphillips, 2013-12-18 18:28:15]

Created Revert of Change SkDecodingImageGenerator API

[commit-bot: I haz the power, 2013-12-18 18:28:25]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/robertphillips@google.com/103753007/1

[commit-bot: I haz the power, 2013-12-18 18:28:31]

Presubmit check for 103753007-1 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')

Was the presubmit check useful? Please send feedback & hate mail to
maruel@chromium.org!

[bsalomon, 2013-12-18 18:32:46]

On 2013/12/18 18:28:31, I haz the power (commit-bot) wrote:
> Presubmit check for 103753007-1 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')
> 
> Was the presubmit check useful? Please send feedback & hate mail to
> maruel@chromium.org!

public header lgtm

[commit-bot: I haz the power, 2013-12-18 18:33:05]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/robertphillips@google.com/103753007/1

[commit-bot: I haz the power, 2013-12-18 18:33:21]

Change committed as 12747