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

ios/chrome/browser/web/blocked_popup_tab_helper_unittest.mm

 // 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.
 
 #import "ios/chrome/browser/web/blocked_popup_tab_helper.h"
 
 #include "base/memory/ptr_util.h"
 #include "components/content_settings/core/browser/host_content_settings_map.h"
 #include "components/infobars/core/confirm_infobar_delegate.h"
 #include "components/infobars/core/infobar.h"
 #include "components/infobars/core/infobar_manager.h"
 #include "ios/chrome/browser/browser_state/test_chrome_browser_state.h"
 #include "ios/chrome/browser/content_settings/host_content_settings_map_factory.h"
 #include "ios/chrome/browser/infobars/infobar_manager_impl.h"
 #import "ios/chrome/browser/web/chrome_web_test.h"
 #import "ios/web/public/test/fakes/test_navigation_manager.h"
 #import "ios/web/public/test/fakes/test_web_state.h"
 #import "ios/web/public/test/fakes/test_web_state_delegate.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "url/gurl.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 using web::WebState;
 
 // Test fixture for BlockedPopupTabHelper class.
 class BlockedPopupTabHelperTest : public ChromeWebTest {
  protected:
   void SetUp() override {
     ChromeWebTest::SetUp();
     web_state()->SetDelegate(&web_state_delegate_);
     BlockedPopupTabHelper::CreateForWebState(web_state());
     InfoBarManagerImpl::CreateForWebState(web_state());
@@ skipping 107 matching lines @@
   GetBlockedPopupTabHelper()->HandlePopup(test_url, web::Referrer());
   ASSERT_EQ(1U, GetInfobarManager()->infobar_count());
   EXPECT_TRUE(IsObservingSources());
 
   // Dismiss the infobar and check that the tab helper no longer has any
   // registered observers.
   GetInfobarManager()->infobar_at(0)->RemoveSelf();
   EXPECT_EQ(0U, GetInfobarManager()->infobar_count());
   EXPECT_FALSE(IsObservingSources());
 }