Remove deprecated STYLE_NATIVE_TEXTBUTTON.

Remove the STYLE_NATIVE_TEXTBUTTON native style enum.
STYLE_NATIVE_TEXTBUTTON was replaced by STYLE_BUTTON in M29.
See http://crrev.com/194673 for the effective deprecation.
Uses STYLE_BUTTON in client callsites, remove old code.

BUG=155363
TEST=No behavior or appearance changes.
R=sky@chromium.org
TBR=pfeldman@chromium.org

Review URL: https://codereview.chromium.org/137383003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244884 0039d316-1c4b-4281-b951-d872f2087c98
Generate windows policy files only on windows.

Speeds up running grit on this step from 53s to 40s on my Mac.

BUG=

Review URL: https://codereview.chromium.org/137393007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244885 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 244885