Makes -init and -setType: available in CollectionViewItem

ios/chrome/browser/ui/collection_view/cells/collection_view_item+collection_view_controller.h

Index: ios/chrome/browser/ui/collection_view/cells/collection_view_item+collection_view_controller.h
diff --git a/ios/chrome/browser/ui/collection_view/cells/collection_view_item+collection_view_controller.h b/ios/chrome/browser/ui/collection_view/cells/collection_view_item+collection_view_controller.h
new file mode 100644
index 0000000000000000000000000000000000000000..47d593ce9f07a87cc556666bdd2bb1b0b467f4e2
--- /dev/null
+++ b/ios/chrome/browser/ui/collection_view/cells/collection_view_item+collection_view_controller.h
@@ -0,0 +1,20 @@
+// 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_COLLECTION_VIEW_CELLS_COLLECTION_VIEW_ITEM_COLLECTION_VIEW_CONTROLLER_H_
+#define IOS_CHROME_BROWSER_UI_COLLECTION_VIEW_CELLS_COLLECTION_VIEW_ITEM_COLLECTION_VIEW_CONTROLLER_H_
+
+#import <Foundation/Foundation.h>
+
+#import "ios/chrome/browser/ui/collection_view/cells/collection_view_item.h"
+
+// CollectionViewItem category exposing overridable type property meant only for
+// CollectionViewController instances in order to facilitate their bookkeeping.

[lpromero, 2017/04/14 11:33:58]

Maybe rephrase in a more active voice:

Items can be created with a default item type but they need to have a valid item
type to be inserted in the model. Only the CollectionViewController managing
those items is allowed to set the item type.

[Moe, 2017/04/17 16:34:14]

Done.

+@interface CollectionViewItem (CollectionViewController)
+
+@property(nonatomic, readwrite, assign) NSInteger type;
+
+@end
+
+#endif  // IOS_CHROME_BROWSER_UI_COLLECTION_VIEW_CELLS_COLLECTION_VIEW_ITEM_COLLECTION_VIEW_CONTROLLER_H_