Remove SK_IGNORE_DW_GRAY_FIX

Remove SK_IGNORE_DW_GRAY_FIX.

Before this change when the user asked Skia for anti-aliased but not
subpixel anti-aliased glyphs with DirectWrite the user would always get
the subpixel anti-aliased glyphs but downsampled (the three channels of
subpixel alpha per pixel averaged into one channel of alpha per pixel).
With the DirectWrite shipped in Windows 8 and later there is a new
interface which allows Skia to obtain the single channel anti-aliased
alpha directly. The primary difference from using this method is that
subpixel smoothing (ClearType, aka a blur) is not applied. This provides
less blurry glyphs.

[bungeman-skia, 2017-03-17 22:08:57]

bungeman@google.com changed reviewers:
+ drott@chromium.org

[bungeman-skia, 2017-03-17 22:08:58]

This should change nothing on win7, but improve all the anti-aliased glyphs on
win10.

[drott, 2017-03-20 09:20:29]

On 2017/03/17 at 22:08:58, bungeman wrote:
> This should change nothing on win7, but improve all the anti-aliased glyphs on
win10.

LGTM, I can do the rebaselines when I am done with the gasp table ones. So the
difference is that the grayscale antialiasing values are now coming from DWrite
directly, instead of computing them from RGB values, is that right? I think for
tracking purpose, we should explain this a little more in the commit msg, and
file a bug for reference. If you'd like me to, I can take over the CL when I add
the baselines. Thank you for another Windows font rendering improvement.

[bungeman-skia, 2017-03-20 13:46:10]

Description was changed from

==========
Remove SK_IGNORE_DW_GRAY_FIX
==========

to

==========
Remove SK_IGNORE_DW_GRAY_FIX.

Before this change when the user asked Skia for anti-aliased but not subpixel
anti-aliased glyphs with DirectWrite the user would always get the subpixel
anti-aliased glyphs but downsampled (the three channels of subpixel alpha per
pixel averaged into one channel of alpha per pixel). With the DirectWrite
shipped in Windows 8 and later there is a new interface which allows Skia to
obtain the single channel anti-aliased alpha directly. The primary difference
from using this method is that subpixel smoothing (ClearType, aka a blur) is not
applied. This provides less blurry glyphs.
==========

[bungeman-skia, 2017-03-20 14:12:34]

Description was changed from

==========
Remove SK_IGNORE_DW_GRAY_FIX.

Before this change when the user asked Skia for anti-aliased but not subpixel
anti-aliased glyphs with DirectWrite the user would always get the subpixel
anti-aliased glyphs but downsampled (the three channels of subpixel alpha per
pixel averaged into one channel of alpha per pixel). With the DirectWrite
shipped in Windows 8 and later there is a new interface which allows Skia to
obtain the single channel anti-aliased alpha directly. The primary difference
from using this method is that subpixel smoothing (ClearType, aka a blur) is not
applied. This provides less blurry glyphs.
==========

to

==========
Remove SK_IGNORE_DW_GRAY_FIX.

Before this change when the user asked Skia for anti-aliased but not
subpixel anti-aliased glyphs with DirectWrite the user would always get
the subpixel anti-aliased glyphs but downsampled (the three channels of
subpixel alpha per pixel averaged into one channel of alpha per pixel).
With the DirectWrite shipped in Windows 8 and later there is a new
interface which allows Skia to obtain the single channel anti-aliased
alpha directly. The primary difference from using this method is that
subpixel smoothing (ClearType, aka a blur) is not applied. This provides
less blurry glyphs.
==========

[drott, 2017-03-29 12:10:55]

Closed, landed in https://chromium-review.googlesource.com/c/459519/