Autofill popup dismissed when page loses focus

The popup for autofill is now never activated, even when clicked.
This allows us to hide it when the page loses focus.
(doing that previously would have caused the popup to be hidden before the click in the popup was sent to the renderer).

Most of the file changes are just renaming focus_on_show to activatable.

TEST=Open a form and make an autofill popup. Focus another window, the popup should disappear. Ensure the autofill still work properly, and the combo-box as well.
BUG=3844, 5830
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=7823

[jcampan, 2009-01-09 19:05:22]

This fix is only for the autofill popup.
Fixing the combo-box popup focus will be done in a later CL as it is more work
than originally thought.

[sky, 2009-01-09 19:16:52]

LGTM