Revert of Revert of add gamma/sRGB to SkImageInfo

Revert of Revert of add gamma/sRGB to SkImageInfo (patchset #1 of https://codereview.chromium.org/512243002/)

Reason for revert:
this revert was premature -- the chrome canary I looked at is old, and newer ones were green. So trying again...

Original issue's description:
> Revert of add gamma/sRGB to SkImageInfo (patchset #4 of https://codereview.chromium.org/514753002/)
> 
> Reason for revert:
> breaks linker on chrome -- may need SK_API, but not sure.
> 
> Original issue's description:
> > add gamma/sRGB to SkImageInfo
> > 
> > BUG=skia:
> > 
> > Committed: https://skia.googlesource.com/skia/+/615c369777258231054840a88cdb74c68c382485
> 
> TBR=bungeman@google.com,bsalomon@google.com
> NOTREECHECKS=true
> NOTRY=true
> BUG=skia:
> 
> Committed: https://skia.googlesource.com/skia/+/dc53701216c0e9f98eacf6c0cda769ebbd200b59

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

Committed: https://skia.googlesource.com/skia/+/e759a2662273fdf52ebbb3822229945eda317e46

[reed1, 2014-08-28 18:56:31]

Created Revert of Revert of add gamma/sRGB to SkImageInfo

[commit-bot: I haz the power, 2014-08-28 18:57:28]

CQ is trying da patch. Follow status at
 https://skia-tree-status.appspot.com/cq/reed@google.com/511363002/1

[commit-bot: I haz the power, 2014-08-28 18:57:38]

Committed patchset #1 (id:1) as e759a2662273fdf52ebbb3822229945eda317e46

[reed1, 2014-08-28 21:41:45]

A revert of this CL (patchset #1) has been created in
https://codereview.chromium.org/513423002/ by reed@google.com.

The reason for reverting is: android builder in chrome reveals the caller using
{ } initialization for SkImageInfo, which this CL now makes illegal. Will have
to fix the call site before I can re-land this..

[reed1, 2014-08-28 21:45:28]

A revert of this CL (patchset #1) has been created in
https://codereview.chromium.org/517113002/ by reed@google.com.

The reason for reverting is: android builder in chrome reveals the caller using
{ } initialization for SkImageInfo, which this CL now makes illegal. Will have
to fix the call site before I can re-land this.