Eliminate the dependence of tts extension API for tts_controller.cc

This is the first patch to move TTS implementation from browser layer
to content. To move TTS to conent, the direct dependence of browser
compoent should be eliminated from TTS classes first.

R=tommi@chromium.org, dmazzoni@chromium.org, sky@chromium.org
BUG=347045

Review URL: https://codereview.chromium.org/181123004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254740 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 254740