BookmarkManager: would crash in Debug mode.
BookmarkManager: would crash in Debug mode.

This is introduced by add
ShowSingletonTab(GURL(chrome::kChromeUIBookmarksURL)) when show
BookmarkManager Panle for tracking convenience.
When brower didn't enable extension, would trigger this checker:
  NOTREACHED() << "We should never get here since the extension should have"
               << "been triggered";

Right now, comment out this checker because we didn't need to
inactive with this page. it would not affect user experience.

reviewed by xingnan.

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser