Keep overlay cast button visible long enough for user action

The overlay cast button should remain visible for some seconds
after the user taps the video, so that they can actually press it.
https://codereview.chromium.org/1156993013/ broke this (as described
in the bug). This reverts that small piece of
https://codereview.chromium.org/1156993013/

BUG=532017

Review URL: https://codereview.chromium.org/1336133004

git-svn-id: svn://svn.chromium.org/blink/trunk@202592 bbb929c8-8fbe-4397-9dbb-9b2b20218538
2 files changed