Translate new UX: set the translate icon visible whenever translation is done

The change of LanguageState::translate_enabled affects the state of Translate icon on the Omnibox, and this icon should be shown after translation.

BUG=324172
TEST=unit_tests --gtest_filter=LanguageStateTest.*

Review URL: https://codereview.chromium.org/104293002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240311 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 240311