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

ios/web/navigation/crw_session_storage_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/web/public/crw_session_storage.h"
 
-#import "base/mac/scoped_nsobject.h"
 #include "base/strings/sys_string_conversions.h"
 #import "ios/web/navigation/navigation_item_impl.h"
 #import "ios/web/navigation/navigation_item_storage_test_util.h"
 #import "ios/web/navigation/serializable_user_data_manager_impl.h"
 #import "ios/web/public/crw_navigation_item_storage.h"
 #include "ios/web/public/referrer.h"
 #import "net/base/mac/url_conversions.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #import "testing/gtest_mac.h"
 #include "testing/platform_test.h"
 #include "third_party/ocmock/gtest_support.h"
 #include "ui/base/page_transition_types.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 // Checks for equality between the item storages in |items1| and |items2|.
 BOOL ItemStorageListsAreEqual(NSArray* items1, NSArray* items2) {
   __block BOOL items_are_equal = items1.count == items2.count;
   if (!items_are_equal)
     return NO;
   [items1 enumerateObjectsUsingBlock:^(CRWNavigationItemStorage* item,
                                        NSUInteger idx, BOOL* stop) {
     items_are_equal &= web::ItemStoragesAreEqual(item, items2[idx]);
     *stop = !items_are_equal;
@@ skipping 26 matching lines @@
 
 class CRWNSessionStorageTest : public PlatformTest {
  protected:
   CRWNSessionStorageTest()
       : session_storage_([[CRWSessionStorage alloc] init]) {
     // Set up |session_storage_|.
     [session_storage_ setHasOpener:YES];
     [session_storage_ setLastCommittedItemIndex:4];
     [session_storage_ setPreviousItemIndex:3];
     // Create an item storage.
-    base::scoped_nsobject<CRWNavigationItemStorage> item_storage(
-        [[CRWNavigationItemStorage alloc] init]);
+    CRWNavigationItemStorage* item_storage =
+        [[CRWNavigationItemStorage alloc] init];
     [item_storage setVirtualURL:GURL("http://init.test")];
     [item_storage setReferrer:web::Referrer(GURL("http://referrer.url"),
                                             web::ReferrerPolicyDefault)];
     [item_storage setTimestamp:base::Time::Now()];
     [item_storage setTitle:base::SysNSStringToUTF16(@"Title")];
     [item_storage
         setDisplayState:web::PageDisplayState(0.0, 0.0, 0.0, 0.0, 0.0)];
     [item_storage
         setPOSTData:[@"Test data" dataUsingEncoding:NSUTF8StringEncoding]];
     [item_storage setHTTPRequestHeaders:@{ @"HeaderKey" : @"HeaderValue" }];
     [session_storage_ setItemStorages:@[ item_storage ]];
     // Create serializable user data.
     std::unique_ptr<web::SerializableUserDataImpl> user_data(
         new web::SerializableUserDataImpl(
             @{ @"key" : @"value" }));
     [session_storage_ setSerializableUserData:std::move(user_data)];
   }
 
  protected:
-  base::scoped_nsobject<CRWSessionStorage> session_storage_;
+  CRWSessionStorage* session_storage_;
 };
 
 // Tests that unarchiving CRWSessionStorage data results in an equivalent
 // storage.
 TEST_F(CRWNSessionStorageTest, EncodeDecode) {
   NSData* data = [NSKeyedArchiver archivedDataWithRootObject:session_storage_];
   id decoded = [NSKeyedUnarchiver unarchiveObjectWithData:data];
   EXPECT_TRUE(SessionStoragesAreEqual(session_storage_, decoded));
 }