Revert 251125 "OneClickSigninHelper::CanOffer checks IsEnableWeb..."

partial revert 251125 which causes crbug/347030

> OneClickSigninHelper::CanOffer checks IsEnableWebBasedSignin
> 
> Before, the CanOffer method could return true, while the web based signin was disabled through about:flags. This meant that neither the save password prompt, nor the sign-in interstitial were shown.
> 
> This CL ensures that CanOffer returns false if the web based signing is disabled in about:flags.
> 
> BUG=339804
> 
> Review URL: https://codereview.chromium.org/160363002

TBR=vabr@chromium.org

Review URL: https://codereview.chromium.org/178223014

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253608 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 253608
Fix logic bug in r253520.

This broke the screenshot tests on the Linux GPU bots when
DISPLAY=":0.0".

BUG=
R=kbr@chromium.org
TBR=tonyg@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/182273002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253609 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 253609