WebStateList is an array of web::WebState* wrappers.

ios/shared/chrome/browser/tabs/web_state_list.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_SHARED_CHROME_BROWSER_TABS_WEB_STATE_LIST_H_
+#define IOS_SHARED_CHROME_BROWSER_TABS_WEB_STATE_LIST_H_
+
+#import <Foundation/Foundation.h>
+
+@protocol WebStateHandle;
+
+// Clang format incorrectly formats the <__covariant ObjectType> used
+// to declare WebStateList as a lighweight generic class. Disable it
+// until the underlying issue is fixed (b/34375672).
+// clang-format off
+
+// A generic array of WebStateHandles.
+@interface WebStateList<__covariant ObjectType: id<WebStateHandle>>
+    : NSObject<NSFastEnumeration>
+
+// The number of objects in the array.
+@property(nonatomic, readonly) NSUInteger count;
+
+// The first WebStateHandle in the array.
+@property(nonatomic, readonly) ObjectType firstWebState;
+
+// Inserts |webState| at the end of the array.
+- (void)addWebState:(ObjectType)webState;
+
+// Inserts |webState| into the array at |index|.
+- (void)insertWebState:(ObjectType)webState atIndex:(NSUInteger)index;
+
+// Replaces the WebStateHandle at |index| with |webState|.
+- (void)replaceWebStateAtIndex:(NSUInteger)index
+                  withWebState:(ObjectType)webState;
+
+// Removes all occurrences of |webState| in the array.
+- (void)removeWebState:(ObjectType)webState;
+
+// Returns YES if |webState| is in the array.
+- (BOOL)containsWebState:(ObjectType)webState;
+
+// Returns the WebStateHandle at |index|.
+- (ObjectType)webStateAtIndex:(NSUInteger)index;
+
+// Returns the lowest index whose value is equal to |webState|.
+- (NSUInteger)indexOfWebState:(ObjectType)webState;
+
+@end
+
+// clang-format on
+
+#endif  // IOS_SHARED_CHROME_BROWSER_TABS_WEB_STATE_LIST_H_