[ios] TabCollectionItem

ios/clean/chrome/browser/ui/tab_collection/tab_collection_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_CLEAN_CHROME_BROWSER_UI_TAB_COLLECTION_TAB_COLLECTION_DATA_SOURCE_H_
-#define IOS_CLEAN_CHROME_BROWSER_UI_TAB_COLLECTION_TAB_COLLECTION_DATA_SOURCE_H_
-
-#import <Foundation/Foundation.h>
-
-const int kTabCollectionDataSourceInvalidIndex = -1;
-
-// The data source for tab collection UI.
-// Conceptually the tab collection represents a group of WebState objects (which
-// are ultimately the model-layer representation of a browser tab). The data
-// source must be able to map between indices and WebStates.
-@protocol TabCollectionDataSource<NSObject>
-
-// The number of tabs to be displayed in the collection.
-- (int)numberOfTabs;
-
-// Title for the tab at |index| in the collection.
-- (NSString*)titleAtIndex:(int)index;
-
-// Index for the active tab or kTabCollectionDataSourceInvalidIndex if there is
-// no active tab.
-- (int)indexOfActiveTab;
-
-@end
-
-#endif  // IOS_CLEAN_CHROME_BROWSER_UI_TAB_COLLECTION_TAB_COLLECTION_DATA_SOURCE_H_