Cleanup ContentSuggestions cells

ios/chrome/browser/ui/content_suggestions/content_suggestions_stack_item.h

-// Copyright 2017 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.
-
-#ifndef IOS_CHROME_BROWSER_UI_CONTENT_SUGGESTIONS_CONTENT_SUGGESTIONS_STACK_ITEM_H_
-#define IOS_CHROME_BROWSER_UI_CONTENT_SUGGESTIONS_CONTENT_SUGGESTIONS_STACK_ITEM_H_
-
-#import "ios/chrome/browser/ui/collection_view/cells/collection_view_item.h"
-#import "ios/third_party/material_components_ios/src/components/CollectionCells/src/MaterialCollectionCells.h"
-
-// Item for a suggestions stack item. The stack items show an item on the top
-// and hint that there are other items available. Click on the top item will
-// trigger an action, clicking the rest of the cell another.
-@interface ContentSuggestionsStackItem : CollectionViewItem
-
-// Initialize a suggestions item with a |title| and a |subtitle|. |type| is the
-// type of the item.
-- (instancetype)initWithType:(NSInteger)type
-                       title:(NSString*)title
-                    subtitle:(NSString*)subtitle NS_DESIGNATED_INITIALIZER;
-- (instancetype)initWithType:(NSInteger)type NS_UNAVAILABLE;
-
-@end
-
-// Corresponding cell for a suggestions stack item.
-@interface ContentSuggestionsStackCell : MDCCollectionViewCell
-
-@property(nonatomic, readonly, strong) UIButton* titleButton;
-@property(nonatomic, readonly, strong) UILabel* detailTextLabel;
-
-@end
-
-#endif  // IOS_CHROME_BROWSER_UI_CONTENT_SUGGESTIONS_CONTENT_SUGGESTIONS_STACK_ITEM_H_