Translate new UX: Fix the visual and behavior of 'Done' button

The label is 'Translate' only when the page is not translated in the current language pair, otherwise 'Done'.

When the label is 'Translate', the view state transits to 'Translating' from 'Advanced' after clicking the button, while when 'Done', this transits to the previous view state.

BUG=324696
TEST=unit_tests --gtest_filter=TranslateBubbleViewTest.*

Review URL: https://codereview.chromium.org/98643003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238597 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 238597