Add a footer item for the Content Suggestions

ios/chrome/browser/ui/content_suggestions/content_suggestions_footer_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_FOOTER_ITEM_H_
+#define IOS_CHROME_BROWSER_UI_CONTENT_SUGGESTIONS_CONTENT_SUGGESTIONS_FOOTER_ITEM_H_
+
+#import "ios/chrome/browser/ui/collection_view/cells/collection_view_item.h"
+#import "ios/chrome/browser/ui/content_suggestions/content_suggestion_identifier.h"
+#import "ios/third_party/material_components_ios/src/components/CollectionCells/src/MaterialCollectionCells.h"
+
+// Item for a footer of a Content Suggestions section.
+@interface ContentSuggestionsFooterItem
+    : CollectionViewItem<ContentSuggestionIdentification>
+
+// Initialize a footer with a |title| and an |action|.

[lpromero, 2017/03/13 14:45:14]

Mention that the action will be related to the button.
Note, action makes me think about target/action, i.e. a SEL (selector), and not
a block. Maybe rename in buttonBlock, or just "block" if it's clear enough?

[gambard, 2017/03/14 10:02:42]

Done.

+- (instancetype)initWithType:(NSInteger)type
+                       title:(NSString*)title

[lpromero, 2017/03/13 14:45:14]

Do you prefer this style over the regular init and settable properties? The
second seems more flexible at call site.

[gambard, 2017/03/14 10:02:42]

I usually do init only when the number of argument is < 5.

+                      action:(void (^)())action NS_DESIGNATED_INITIALIZER;

[lpromero, 2017/03/13 14:45:13]

Optional nit: use ProceduralBlock.

[gambard, 2017/03/14 10:02:42]

Done.

+
+- (instancetype)initWithType:(NSInteger)type NS_UNAVAILABLE;
+
+@end
+
+// Corresponding cell for a Content Suggestions' section footer.
+@interface ContentSuggestionsFooterCell : MDCCollectionViewCell
+
+@property(nonatomic, readonly, strong) UIButton* actionButton;
+
+@end
+
+#endif  // IOS_CHROME_BROWSER_UI_CONTENT_SUGGESTIONS_CONTENT_SUGGESTIONS_FOOTER_ITEM_H_