Use label native theme colors for drag images.

Use label native theme colors for drag images.

r280376 changed the button drag image painting code.
The label colors used make the text appear blurry.

Use label native theme colors instead of button colors.
(the black-on-white looks better than black-on-gray)

See before/after pics at http://crbug.com/394245#c4

BUG=394245
TEST=Bookmark/URL drag images look okay.
R=sky@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=283644

[msw, 2014-07-16 19:26:03]

Hey Scott, please take a look; thanks!

[sky, 2014-07-16 21:15:40]

LGTM

[msw, 2014-07-16 21:16:22]

The CQ bit was checked by msw@chromium.org

[commit-bot: I haz the power, 2014-07-16 21:18:28]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/msw@chromium.org/400443002/1

[commit-bot: I haz the power, 2014-07-17 04:35:14]

Change committed as 283644