Fixes several focus issue with popup in the extensions' browser actions:
- when opening a browser action popup, it gets the focus.
- tab traversal now works in the popup
- pressing esc closes the popup (if the keyboard event is not processed by the page)

BUG=22654, 28087, 28086
TEST=Create an extension with a browser extension that shows a popup. Make the popup
     so that it has a textfield (that gets focused when the popup show) and a button.
     Install the extension. Open the popup, the textfield should have focus. Press
     tab, the focus should go to the button. Press Esc, the popup should be closed.

Review URL: http://codereview.chromium.org/402036

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@32335 0039d316-1c4b-4281-b951-d872f2087c98
5 files changed