[ObjC ARC] Converts ios/chrome/browser/web:unit_tests_internal to ARC.

ios/chrome/browser/web/chrome_web_client_unittest.mm

 // Copyright (c) 2014 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.
 
 #include "ios/chrome/browser/web/chrome_web_client.h"
 
 #import <UIKit/UIKit.h>
 
 #include <memory>
 
-#include "base/mac/scoped_nsobject.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/string_split.h"
 #include "base/strings/sys_string_conversions.h"
 #include "ios/web/public/test/fakes/test_browser_state.h"
 #import "ios/web/public/test/js_test_util.h"
 #include "ios/web/public/test/scoped_testing_web_client.h"
 #include "ios/web/public/test/web_test.h"
 #import "ios/web/public/web_view_creation_util.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/gtest_mac.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 
 // Test fixture for testing ChromeWebClient.
 typedef web::WebTest ChromeWebClientTest;
 
 TEST_F(ChromeWebClientTest, UserAgent) {
   std::vector<std::string> pieces;
 
   // Check if the pieces of the user agent string come in the correct order.
   ChromeWebClient web_client;
@@ skipping 45 matching lines @@
   web::ScopedTestingWebClient web_client(base::MakeUnique<ChromeWebClient>());
   NSString* script = web_client.Get()->GetEarlyPageScript(&browser_state);
   web::ExecuteJavaScript(web_view, script);
   EXPECT_NSEQ(@"object",
               web::ExecuteJavaScript(web_view, @"typeof __gCrWeb.print"));
   EXPECT_NSEQ(@"undefined", web::ExecuteJavaScript(
                                 web_view, @"typeof __gCrWeb.windowOpenFix"));
 }
 
 }  // namespace