I'm working on autocomplete edit view which does not use native controls for Chromeos and Touch UI.

The goal of this refactoring is to make it easy to swap  AutocompleteEditView implementation between Gtk based impl and Views based one. This is 1st phrase and there will be more refacotring needed to implement AutocompleteEditViewViews.

- Added factory method AutocompleteEditViewGtk::Create,
  which hides initialization details for gtk based impl.
- Moved gtk specific accessibilty code to AutocompleteEditViewGtk.
- Added TOOLKIT_VIWES only methods to AutocompleteEditView
  to hide platform specific implementation. (AddToView, CommitInstatntSuggestion/SetInstantSuggestion)

BUG=none
TEST=none no functional change. all tests should pass.

Review URL: http://codereview.chromium.org/6036004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@70746 0039d316-1c4b-4281-b951-d872f2087c98