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

ios/chrome/browser/tabs/tab_model.h

Index: ios/chrome/browser/tabs/tab_model.h
diff --git a/ios/chrome/browser/tabs/tab_model.h b/ios/chrome/browser/tabs/tab_model.h
index bb888ac51612c6b6585ebfb0493e9d732149ea76..e2e0a8fe112a3342ee07343e5b5760001e800d1e 100644
--- a/ios/chrome/browser/tabs/tab_model.h
+++ b/ios/chrome/browser/tabs/tab_model.h
@@ -10,8 +10,6 @@
 
 #include <memory>
 
-#import "ios/chrome/browser/tabs/tab.h"
-#import "ios/shared/chrome/browser/tabs/web_state_list.h"
 #import "ios/web/public/navigation_manager.h"
 #include "ui/base/page_transition_types.h"
 
@@ -19,6 +17,7 @@ class GURL;
 class SessionID;
 @class SessionServiceIOS;
 @class SessionWindowIOS;
+@class Tab;
 @protocol TabModelObserver;
 class TabModelSyncedWindowDelegate;
 class TabUsageRecorder;
@@ -82,7 +81,7 @@ NSUInteger const kTabPositionAutomatically = NSNotFound;
 // The model knows about the currently selected tab in order to maintain
 // consistency between multiple views that need the current tab to be
 // synchronized.
-@interface TabModel : WebStateList<Tab*>
+@interface TabModel : NSObject<NSFastEnumeration>
 
 // Currently active tab.
 @property(nonatomic, weak) Tab* currentTab;
@@ -113,6 +112,9 @@ NSUInteger const kTabPositionAutomatically = NSNotFound;
 // NO if the model has at least one tab.
 @property(nonatomic, readonly, getter=isEmpty) BOOL empty;
 
+// Determines the number of tabs in the model.
+@property(nonatomic, readonly) NSUInteger count;
+
 // Initializes tabs from a restored session. |-setCurrentTab| needs to be called
 // in order to display the views associated with the tabs. Waits until the views
 // are ready. |browserState| cannot be nil. |service| cannot be nil; this class