Turn the Translate icon on only when the translation is succesfully done

BUG=313117
TEST=unit_tests --gtest_filter=LanguageStateTest.*

Review URL: https://codereview.chromium.org/73173007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236412 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 236412