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

ash/common/test/test_shelf_item_delegate.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/common/test/test_shelf_item_delegate.h"
 
 #include "ash/common/wm_window.h"
 
 namespace ash {
 namespace test {
@@ skipping 16 matching lines @@
 }
 
 base::string16 TestShelfItemDelegate::GetTitle() {
   return window_ ? window_->GetTitle() : base::string16();
 }
 
 ShelfMenuModel* TestShelfItemDelegate::CreateApplicationMenu(int event_flags) {
   return nullptr;
 }
 
-bool TestShelfItemDelegate::CanPin() const {
-  return true;
-}
-
 void TestShelfItemDelegate::Close() {}
 
 }  // namespace test
 }  // namespace ash