[ObjC ARC] Converts ios/web:ios_web_navigation_unittests to ARC.

ios/web/navigation/navigation_item_impl_unittest.mm

 // Copyright 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.
 
 #import "ios/web/navigation/navigation_item_impl.h"
 
 #include <memory>
 
 #include "base/logging.h"
-#import "base/mac/scoped_nsobject.h"
 #include "base/strings/utf_string_conversions.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #import "testing/gtest_mac.h"
 #include "testing/platform_test.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace web {
 namespace {
 
 const char kItemURLString[] = "http://init.test";
 static NSString* const kHTTPHeaderKey1 = @"key1";
 static NSString* const kHTTPHeaderKey2 = @"key2";
 static NSString* const kHTTPHeaderValue1 = @"value1";
 static NSString* const kHTTPHeaderValue2 = @"value2";
 
 class NavigationItemTest : public PlatformTest {
@@ skipping 133 matching lines @@
 
   title = NavigationItemImpl::GetDisplayTitleForURL(GURL("file://foo.org/"));
   EXPECT_EQ("file://foo.org/", base::UTF16ToUTF8(title));
 
   title = NavigationItemImpl::GetDisplayTitleForURL(GURL("file://foo/1.gz"));
   EXPECT_EQ("1.gz", base::UTF16ToUTF8(title));
 }
 
 }  // namespace
 }  // namespace web