Add ContentSuggestionsMediator

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

+// Copyright 2017 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_DATA_SOURCE_H_
+#define IOS_CHROME_BROWSER_UI_CONTENT_SUGGESTIONS_CONTENT_SUGGESTIONS_DATA_SOURCE_H_
+
+@class ContentSuggestion;
+@protocol ContentSuggestionsDataSink;
+
+// DataSource for the content suggestions. Provides the suggestions data in a
+// format compatible with Objective-C.
+@protocol ContentSuggestionsDataSource
+
+// The data sink that will be notified when the data change.
+@property(nonatomic, weak) id<ContentSuggestionsDataSink> dataSink;
+
+// Returns all the data currently available. Returns an empty array if nothing
+// is available.
+- (NSArray<ContentSuggestion*>*)allSuggestions;
+
+@end
+
+#endif  // IOS_CHROME_BROWSER_UI_CONTENT_SUGGESTIONS_CONTENT_SUGGESTIONS_DATA_SOURCE_H_