Clean up ash::ShellTestApi

ash/shelf/shelf_view_unittest.cc

Index: ash/shelf/shelf_view_unittest.cc
diff --git a/ash/shelf/shelf_view_unittest.cc b/ash/shelf/shelf_view_unittest.cc
index 10312750af7300e1155ef50dab3a523180b150c3..59765d81dc9dcde95c49c811379d31e2b7581411 100644
--- a/ash/shelf/shelf_view_unittest.cc
+++ b/ash/shelf/shelf_view_unittest.cc
@@ -30,7 +30,6 @@
 #include "ash/test/overflow_bubble_view_test_api.h"
 #include "ash/test/shelf_test_api.h"
 #include "ash/test/shelf_view_test_api.h"
-#include "ash/test/shell_test_api.h"
 #include "ash/test/test_shelf_delegate.h"
 #include "ash/test/test_shelf_item_delegate.h"
 #include "ash/test/test_shell_delegate.h"
@@ -314,8 +313,7 @@ class ShelfViewTest : public AshTestBase {
 
   void SetUp() override {
     AshTestBase::SetUp();
-    ShellTestApi test_api(Shell::GetInstance());
-    model_ = test_api.shelf_model();
+    model_ = WmShell::Get()->shelf_model();
     Shelf* shelf = Shelf::ForPrimaryDisplay();
     shelf_view_ = ShelfTestAPI(shelf).shelf_view();