[Autofill] Fix Flickering in Autofill UI

Reuse the UI view if possible, otherwise every change will cause the
popup to flicker.

BUG=236343

Review URL: https://chromiumcodereview.appspot.com/14640011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@197707 0039d316-1c4b-4281-b951-d872f2087c98
5 files changed