Add ContentSuggestionsMediator

ios/chrome/browser/ui/content_suggestions/content_suggestions_collection_updater.h

Index: ios/chrome/browser/ui/content_suggestions/content_suggestions_collection_updater.h
diff --git a/ios/chrome/browser/ui/content_suggestions/content_suggestions_collection_updater.h b/ios/chrome/browser/ui/content_suggestions/content_suggestions_collection_updater.h
index b453f170f3aef3d11c1ac72ee57dae3d5233188f..29615fda56c5ab1a48b1462204edd6f5ada6be31 100644
--- a/ios/chrome/browser/ui/content_suggestions/content_suggestions_collection_updater.h
+++ b/ios/chrome/browser/ui/content_suggestions/content_suggestions_collection_updater.h
@@ -9,6 +9,7 @@
 
 #import "ios/chrome/browser/ui/collection_view/collection_view_model.h"
 
+@protocol ContentSuggestionsDataSource;
 @class ContentSuggestionsViewController;
 
 // Enum defining the ItemType of this ContentSuggestionsCollectionUpdater.
@@ -24,6 +25,12 @@ typedef NS_ENUM(NSInteger, ItemType) {
 // 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)