mash: Remove ShelfDelegate; move functions to ShelfModel.

ash/mus/shell_delegate_mus.cc

Index: ash/mus/shell_delegate_mus.cc
diff --git a/ash/mus/shell_delegate_mus.cc b/ash/mus/shell_delegate_mus.cc
index 63137bb378f4daae87aea5ccb66e4a4154154139..8d7679b3af3df16e0bd0da0840478191aee476aa 100644
--- a/ash/mus/shell_delegate_mus.cc
+++ b/ash/mus/shell_delegate_mus.cc
@@ -9,7 +9,6 @@
 #include "ash/gpu_support_stub.h"
 #include "ash/mus/accessibility_delegate_mus.h"
 #include "ash/mus/context_menu_mus.h"
-#include "ash/mus/shelf_delegate_mus.h"
 #include "ash/mus/system_tray_delegate_mus.h"
 #include "ash/mus/wallpaper_delegate_mus.h"
 #include "ash/palette_delegate.h"
@@ -103,10 +102,6 @@ void ShellDelegateMus::OpenUrlFromArc(const GURL& url) {
   NOTIMPLEMENTED();
 }
 
-ShelfDelegate* ShellDelegateMus::CreateShelfDelegate(ShelfModel* model) {
-  return new ShelfDelegateMus();
-}
-
 SystemTrayDelegate* ShellDelegateMus::CreateSystemTrayDelegate() {
   return new SystemTrayDelegateMus();
 }