Fixing a lifetime issue for Speech Recognition Bubble

      It seems that on a slow XP machine the view can be deleted before the
Impl. Fixed by a simple observer pattern.

BUG=352851

Review URL: https://codereview.chromium.org/213153002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@261737 0039d316-1c4b-4281-b951-d872f2087c98