Rename a pref name for kLanguageHotkeyNextEngine.
Rename a pref name for kLanguageHotkeyNextEngine.

This change is necessary since the "settings.language.hotkey_next_engine" user pref for some users is polluted (i.e. the bad value "Shift+space" is written) and currently there's no way for users to reset the value. Please check issue 3009 for details.

BUG=chromium-os:3009
TEST=none

Review URL: http://codereview.chromium.org/2055005

git-svn-id: http://src.chromium.org/svn/trunk/src@46808 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: a2830b2995cc342b915b3867f52aae7db253c9f7
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser