Hide the ink for the custom-design cells

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 173 matching lines @@
   if ([self.collectionUpdater isMostVisitedSection:section]) {
     return content_suggestions::spacingBetweenTiles();
   }
   return [super collectionView:collectionView
                                    layout:collectionViewLayout
       minimumLineSpacingForSectionAtIndex:section];
 }
 
 #pragma mark - MDCCollectionViewStylingDelegate
 
+// TODO(crbug.com/724493): Use collectionView:hidesInkViewAtIndexPath: when it
+// is fixed. For now hidding the ink prevent cell interaction.
+- (UIColor*)collectionView:(UICollectionView*)collectionView
+       inkColorAtIndexPath:(NSIndexPath*)indexPath {
+  if ([self.collectionUpdater
+          shouldUseCustomStyleForSection:indexPath.section]) {
+    return [UIColor clearColor];
+  }
+  return nil;
+}
+
 - (UIColor*)collectionView:(nonnull UICollectionView*)collectionView
     cellBackgroundColorAtIndexPath:(nonnull NSIndexPath*)indexPath {
   if ([self.collectionUpdater
           shouldUseCustomStyleForSection:indexPath.section]) {
     return [UIColor clearColor];
   }
   return [UIColor whiteColor];
 }
 
 - (BOOL)collectionView:(nonnull UICollectionView*)collectionView
@@ skipping 58 matching lines @@
 - (void)addEmptySectionPlaceholderIfNeeded:(NSInteger)section {
   if ([self.collectionViewModel numberOfItemsInSection:section] > 0)
     return;
 
   NSIndexPath* emptyItem =
       [self.collectionUpdater addEmptyItemForSection:section];
   [self.collectionView insertItemsAtIndexPaths:@[ emptyItem ]];
 }
 
 @end