Suggested Articles can be dismissed

ios/chrome/browser/ui/content_suggestions/content_suggestions_view_controller.mm

 // 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.
 
 #import "ios/chrome/browser/ui/content_suggestions/content_suggestions_view_controller.h"
 
 #include "base/mac/foundation_util.h"
 #import "ios/chrome/browser/ui/collection_view/cells/MDCCollectionViewCell+Chrome.h"
 #import "ios/chrome/browser/ui/collection_view/cells/collection_view_item.h"
 #import "ios/chrome/browser/ui/collection_view/collection_view_model.h"
@@ skipping 23 matching lines @@
 // according to |expand|.
 - (void)expand:(BOOL)expand cell:(UICollectionViewCell*)cell;
 
 @end
 
 @implementation ContentSuggestionsViewController
 
 @synthesize suggestionCommandHandler = _suggestionCommandHandler;
 @synthesize collectionUpdater = _collectionUpdater;
 
+#pragma mark - Public
+
 - (instancetype)initWithStyle:(CollectionViewControllerStyle)style
                    dataSource:(id<ContentSuggestionsDataSource>)dataSource {
   self = [super initWithStyle:style];
   if (self) {
     _collectionUpdater = [[ContentSuggestionsCollectionUpdater alloc]
         initWithDataSource:dataSource];
   }
   return self;
 }
 
+- (void)dismissEntryAtIndexPath:(NSIndexPath*)indexPath {
+  if (!indexPath)
+    return;
+
+  [self.collectionView performBatchUpdates:^{
+    [self collectionView:self.collectionView
+        willDeleteItemsAtIndexPaths:@[ indexPath ]];

[lpromero, 2017/03/06 10:29:00]

Why do you call this? So that the item is removed from the model?
Should willDelete be outside performBatchUpdates and the deleteItems call be
inside?
Actually, why do you need the performBatchUpdates?

[gambard, 2017/03/06 12:16:00]

I use performBatchUpdates defensively because the UIColllectionView does not
support updating multiple cells in the same runloop.
I don't understand why willDelete (which delete items from the model) should be
outside? I think you were the one asking me to put it inside the
performBatchUpdate (in Reading List).

[lpromero, 2017/03/06 13:02:30]

Can -dismissEntryAtIndexPath: be called several times in a same turn of run
loop? Will calls be queued and run in their own turn?
Ah I remember:
https://github.com/material-components/material-components-ios/blob/620b5be11...
Thanks for the refresher!

[gambard, 2017/03/06 17:25:33]

For now it should not be called in the same turn of runloop. But in the future
maybe (and this API is public so I don't want to enforce something like "spin
the runloop between two call of this method").
By having performBatchUpdates, the updates will queue nicely if called during
the same turn of runloop.

+
+    [self.collectionView deleteItemsAtIndexPaths:@[ indexPath ]];
+  }
+                                completion:nil];
+}
+
 #pragma mark - UIViewController
 
 - (void)viewDidLoad {
   [super viewDidLoad];
 
   _collectionUpdater.collectionViewController = self;
 
   self.collectionView.delegate = self;
   self.styler.cellStyle = MDCCollectionViewCellStyleCard;
 
@@ skipping 126 matching lines @@
 
   if ([self.collectionUpdater contentSuggestionTypeForItem:touchedItem] !=
       ContentSuggestionTypeArticle) {
     // Only trigger context menu on articles.
     return;
   }
 
   ContentSuggestionsArticleItem* articleItem =
       base::mac::ObjCCastStrict<ContentSuggestionsArticleItem>(touchedItem);
 
-  [self.suggestionCommandHandler displayContextMenuForArticle:articleItem
-                                                      atPoint:touchLocation];
+  [self.suggestionCommandHandler
+      displayContextMenuForArticle:articleItem
+                           atPoint:touchLocation
+                       atIndexPath:touchedItemIndexPath];
 }
 
 @end