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

ios/shared/chrome/browser/tabs/BUILD.gn

Index: ios/shared/chrome/browser/tabs/BUILD.gn
diff --git a/ios/shared/chrome/browser/tabs/BUILD.gn b/ios/shared/chrome/browser/tabs/BUILD.gn
deleted file mode 100644
index 834cbc250c5e087c432c70fdc10a8d660761ee1f..0000000000000000000000000000000000000000
--- a/ios/shared/chrome/browser/tabs/BUILD.gn
+++ /dev/null
@@ -1,16 +0,0 @@
-# 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.
-
-source_set("tabs") {
-  sources = [
-    "web_state_handle.h",
-    "web_state_list.h",
-    "web_state_list.mm",
-  ]
-  deps = [
-    "//base",
-  ]
-  libs = [ "Foundation.framework" ]
-  configs += [ "//build/config/compiler:enable_arc" ]
-}