Allow CollectionViewModel/Controller queries without SectionIdentifier

ios/chrome/browser/ui/collection_view/collection_view_model.h

 // Copyright 2016 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_COLLECTION_VIEW_MODEL_H_
 #define IOS_CHROME_BROWSER_UI_COLLECTION_VIEW_COLLECTION_VIEW_MODEL_H_
 
 #import <UIKit/UIKit.h>
 
 @class CollectionViewItem;
@@ skipping 152 matching lines @@
 // Returns the index path for |itemType| in the section for |sectionIdentifier|
 // at |index|.
 - (NSIndexPath*)indexPathForItemType:(NSInteger)itemType
                    sectionIdentifier:(NSInteger)sectionIdentifier
                              atIndex:(NSUInteger)index;
 
 #pragma mark Query index paths from items
 
 // Returns whether |item| exists in section for |sectionIdentifier|.
 - (BOOL)hasItem:(ObjectType)item
     inSectionWithIdentifier:(NSInteger)sectionIdentifier;

[lpromero, 2017/05/02 13:18:08]

Shouldn't we remove that one too?

[gambard, 2017/05/02 13:24:21]

Well, I hesitated and it would make sense to have a lookup to know in which
section an item is no?

[lpromero, 2017/05/02 13:43:21]

Makes sense, especially in your case.

 
+// Returns whether |item| exists.
+- (BOOL)hasItem:(ObjectType)item;
+
 // Returns the index path corresponding to the given |item|.
-- (NSIndexPath*)indexPathForItem:(ObjectType)item
-         inSectionWithIdentifier:(NSInteger)sectionIdentifier;
+- (NSIndexPath*)indexPathForItem:(ObjectType)item;
 
 #pragma mark UICollectionView data sourcing
 
 // Returns the number of collection view sections.
 - (NSInteger)numberOfSections;
 
 // Returns the number of collection view items in the given section.
 - (NSInteger)numberOfItemsInSection:(NSInteger)section;
 
 @end
 
 #endif  // IOS_CHROME_BROWSER_UI_COLLECTION_VIEW_COLLECTION_VIEW_MODEL_H_