Makes -init and -setType: available in CollectionViewItem

ios/chrome/browser/ui/collection_view/cells/collection_view_item.mm

Index: ios/chrome/browser/ui/collection_view/cells/collection_view_item.mm
diff --git a/ios/chrome/browser/ui/collection_view/cells/collection_view_item.mm b/ios/chrome/browser/ui/collection_view/cells/collection_view_item.mm
index f4cc10ddd0d3fb2f6d1e702168e3f447a94cf8ee..a810ba50e54c4f863d81f74067ae3b8dc8335e55 100644
--- a/ios/chrome/browser/ui/collection_view/cells/collection_view_item.mm
+++ b/ios/chrome/browser/ui/collection_view/cells/collection_view_item.mm
@@ -5,6 +5,7 @@
 #import "ios/chrome/browser/ui/collection_view/cells/collection_view_item.h"
 
 #import "base/logging.h"
+#import "ios/chrome/browser/ui/collection_view/cells/collection_view_item+Private.h"
 #import "ios/third_party/material_components_ios/src/components/CollectionCells/src/MaterialCollectionCells.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
@@ -26,8 +27,7 @@
 }
 
 - (instancetype)init {
-  NOTREACHED();
-  return nil;
+  return [self initWithType:0];
 }
 
 - (void)setCellClass:(Class)cellClass {
@@ -42,3 +42,11 @@
 }
 
 @end
+
+@implementation CollectionViewItem (Private)
+
+- (void)setType:(NSInteger)type {
+  _type = type;

[lpromero, 2017/04/13 21:42:59]

DCHECK type >= kItemTypeEnumStart.

[Moe, 2017/04/14 02:55:38]

This would create a dependency cycle:
//i/c/b/u/collection_view/cells -> //i/c/b/u/collection_view ->
//i/c/b/u/collection_view/cells
I don't think this check is necessary here since it's done in the
CollectionViewModel. 

[lpromero, 2017/04/14 11:37:11]

Acknowledged.

+}
+
+@end