Add ContentSuggestionsMediator

ios/chrome/browser/ui/content_suggestions/content_suggestions_collection_updater.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_CONTENT_SUGGESTIONS_CONTENT_SUGGESTIONS_COLLECTION_UPDATER_H_
 #define IOS_CHROME_BROWSER_UI_CONTENT_SUGGESTIONS_CONTENT_SUGGESTIONS_COLLECTION_UPDATER_H_
 
 #import <UIKit/UIKit.h>
 
 #import "ios/chrome/browser/ui/collection_view/collection_view_model.h"
 
+@protocol ContentSuggestionsDataSource;
 @class ContentSuggestionsViewController;
 
 // Enum defining the ItemType of this ContentSuggestionsCollectionUpdater.
 typedef NS_ENUM(NSInteger, ItemType) {
   ItemTypeText = kItemTypeEnumZero,
   ItemTypeArticle,
   ItemTypeExpand,
   ItemTypeStack,
   ItemTypeFavicon,
 };
 
 // Updater for a CollectionViewController populating it with some items and
 // handling the items addition.
 @interface ContentSuggestionsCollectionUpdater : NSObject
 
+// Initialize with the |dataSource| used to get the data.
+- (instancetype)initWithDataSource:(id<ContentSuggestionsDataSource>)dataSource
+    NS_DESIGNATED_INITIALIZER;
+
+- (instancetype)init NS_UNAVAILABLE;
+
 // |collectionViewController| this Updater will update. Needs to be set before
 // adding items.
 @property(nonatomic, assign)
     ContentSuggestionsViewController* collectionViewController;
 
 // Adds a text item with a |title| and a |subtitle| in the section numbered
 // |section|. If |section| is greater than the current number of section, it
 // will add a new section at the end.
 - (void)addTextItem:(NSString*)title
            subtitle:(NSString*)subtitle
           toSection:(NSInteger)inputSection;
 
 // Returns whether the section should use the default, non-card style.
 - (BOOL)shouldUseCustomStyleForSection:(NSInteger)section;
 
 @end
 
 #endif  // IOS_CHROME_BROWSER_UI_CONTENT_SUGGESTIONS_CONTENT_SUGGESTIONS_COLLECTION_UPDATER_H_