ash: Convert ShelfDelegate to use WmShelf* instead of Shelf*

ash/shell/shell_delegate_impl.cc

Index: ash/shell/shell_delegate_impl.cc
diff --git a/ash/shell/shell_delegate_impl.cc b/ash/shell/shell_delegate_impl.cc
index 874552e180ad4a64dee173afd8cab6cd240a6054..0b8d3db57af497016e20e0773e1763a310c385c4 100644
--- a/ash/shell/shell_delegate_impl.cc
+++ b/ash/shell/shell_delegate_impl.cc
@@ -19,9 +19,9 @@
 #include "ash/shell.h"
 #include "ash/shell/context_menu.h"
 #include "ash/shell/example_factory.h"
-#include "ash/shell/shelf_delegate_impl.h"
 #include "ash/shell/toplevel_window.h"
 #include "ash/test/test_keyboard_ui.h"
+#include "ash/test/test_shelf_delegate.h"
 #include "base/memory/ptr_util.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/utf_string_conversions.h"
@@ -230,7 +230,7 @@ app_list::AppListPresenter* ShellDelegateImpl::GetAppListPresenter() {
 }
 
 ShelfDelegate* ShellDelegateImpl::CreateShelfDelegate(ShelfModel* model) {
-  shelf_delegate_ = new ShelfDelegateImpl();
+  shelf_delegate_ = new test::TestShelfDelegate(model);
   return shelf_delegate_;
 }