Fix Desktop Capture API to close the picker dialog automatically.

BUG=334449

Review URL: https://codereview.chromium.org/138183005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246518 0039d316-1c4b-4281-b951-d872f2087c98
Re-enable custom user32 custom imports on VS2013.

It looks like this has been fixed in the Update 1 of VS2013

(this is a revert of https://codereview.chromium.org/27072004)

R=siggi@chromium.org, scottmg@chromium.org
BUG=309845

Review URL: https://codereview.chromium.org/144893004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246519 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246519