Allow CollectionViewModel/Controller queries without SectionIdentifier

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

Index: ios/chrome/browser/ui/collection_view/collection_view_model.h
diff --git a/ios/chrome/browser/ui/collection_view/collection_view_model.h b/ios/chrome/browser/ui/collection_view/collection_view_model.h
index 274cf048f76a12e6b2779e2bbdf50652fe44acad..8ffbbf0a68773ba713a820feb583fa5816c244ee 100644
--- a/ios/chrome/browser/ui/collection_view/collection_view_model.h
+++ b/ios/chrome/browser/ui/collection_view/collection_view_model.h
@@ -172,9 +172,11 @@ const NSInteger kItemTypeEnumZero = 100;
 - (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