Revert of Oilpan: Prepare moving DateTimeChooser to Oilpan

Reverting r176293

Reason for revert:
We need to call closePopup() in the destructor

BUG=401363

Review URL: https://codereview.chromium.org/488173007

git-svn-id: svn://svn.chromium.org/blink/trunk@180901 bbb929c8-8fbe-4397-9dbb-9b2b20218538