Switch a bunch of remaining filters to derive from BrowserMessageFilters so that ResourceMessageFilter doesn't have to know about them and vice versa.  A bunch of small cleanup in the process.  I've added new message files for classes that want their messages dispatched on threads other than the IO.
Review URL: http://codereview.chromium.org/5698008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@69008 0039d316-1c4b-4281-b951-d872f2087c98
36 files changed