Add logging in WebViewImpl::scheduleAnimation

We need to find the missing setNeedsAnimate.

BUG=393331

Review URL: https://codereview.chromium.org/556723004

git-svn-id: svn://svn.chromium.org/blink/trunk@181770 bbb929c8-8fbe-4397-9dbb-9b2b20218538