mash: Replace ShelfItemDelegate::CanPin with ShelfItem::pinned_by_policy.

ash/common/test/test_shelf_item_delegate.cc

Index: ash/common/test/test_shelf_item_delegate.cc
diff --git a/ash/common/test/test_shelf_item_delegate.cc b/ash/common/test/test_shelf_item_delegate.cc
index e7d9cca213e1572a752efc1cdc07104bc5e8730a..f4ee1124581c538dcbf7465c770bd2156de3c893 100644
--- a/ash/common/test/test_shelf_item_delegate.cc
+++ b/ash/common/test/test_shelf_item_delegate.cc
@@ -34,10 +34,6 @@ ShelfMenuModel* TestShelfItemDelegate::CreateApplicationMenu(int event_flags) {
   return nullptr;
 }
 
-bool TestShelfItemDelegate::CanPin() const {
-  return true;
-}
-
 void TestShelfItemDelegate::Close() {}
 
 }  // namespace test