Revert of Add gamma/sRGB tag to SkImageInfo

Revert of Add gamma/sRGB tag to SkImageInfo (patchset #1 id:1 of https://codereview.chromium.org/522813002/)

Reason for revert:
seems to be breaking layout tests in roll

Original issue's description:
> Add gamma/sRGB tag to SkImageInfo
> 
> This reverts commit 64ba5fa1ff428858f803523257cd862f8b33423b.
> 
> BUG=skia:
> 
> Committed: https://skia.googlesource.com/skia/+/c89aa509d6a094bc1b18d73135343819903a9cfb

TBR=reed@google.com
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Committed: https://skia.googlesource.com/skia/+/b44c1895afae516cb851cd1a0cea83343c354ee4

[reed2, 2014-09-01 21:27:51]

Created Revert of Add gamma/sRGB tag to SkImageInfo

[commit-bot: I haz the power, 2014-09-01 21:28:28]

CQ is trying da patch. Follow status at
 https://skia-tree-status.appspot.com/cq/reed@chromium.org/525113005/1

[commit-bot: I haz the power, 2014-09-01 21:28:36]

Committed patchset #1 (id:1) as b44c1895afae516cb851cd1a0cea83343c354ee4

[reed2, 2014-09-02 00:48:32]

Failure from before

http://build.chromium.org/p/tryserver.blink/builders/linux_blink_rel/builds/2...

[ RUN      ] DeferredImageDecoderTest.drawIntoSkPicture
../../third_party/WebKit/Source/platform/graphics/DeferredImageDecoderTest.cpp:172:
Failure
Value of: canvasBitmap.getColor(0, 0)
Actual: 0
Expected: static_cast<SkColor>( (static_cast<U8CPU>(255) << 24) |
(static_cast<U8CPU>(255) << 16) | (static_cast<U8CPU>(255) << 8) |
(static_cast<U8CPU>(255) << 0))
Which is: 4294967295
[  FAILED  ] DeferredImageDecoderTest.drawIntoSkPicture (1 ms)
[1457/1458] DeferredImageDecoderTest.drawIntoSkPicture (1 ms)
[ RUN      ] DeferredImageDecoderTest.decodeOnOtherThread
../../third_party/WebKit/Source/platform/graphics/DeferredImageDecoderTest.cpp:233:
Failure
Value of: canvasBitmap.getColor(0, 0)
Actual: 0
Expected: static_cast<SkColor>( (static_cast<U8CPU>(255) << 24) |
(static_cast<U8CPU>(255) << 16) | (static_cast<U8CPU>(255) << 8) |
(static_cast<U8CPU>(255) << 0))
Which is: 4294967295
[  FAILED  ] DeferredImageDecoderTest.decodeOnOtherThread (1 ms)
[1458/1458] DeferredImageDecoderTest.decodeOnOtherThread (1 ms)
Retrying 2 tests (retry #2)

[reed2, 2014-09-02 01:35:45]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/532583002/ by reed@chromium.org.

The reason for reverting is: Experiment to see resulting failures.