avmedia::getMediaFloater clean-up

Change-Id: I76dcf42267cbb1f028d0501471b569fa6b7b91d5
Fold MediaWindowBaseImpl into MediaWindowImpl

Change-Id: Ie6366d8b1facb39a5f44279f0c49a229b019bcaa
Remove bogus comment

Change-Id: I236e5f3797750f78047957c3dd9984c687ffa0ab
Simplify MediaWindow::mpImpl

Change-Id: Ia466a08a8135a7f2e43278354c767be3a063550a
Fix debug output

Change-Id: I785a3f223bd8897466f9402125df2da07615cd50