[ObjC ARC] Converts ios/chrome/browser/crash_report:unit_tests to ARC.

ios/chrome/browser/crash_report/crash_restore_helper_unittest.mm

 // Copyright 2012 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 <Foundation/Foundation.h>
 
 #include <memory>
 
 #include "base/logging.h"
-#include "base/mac/scoped_nsobject.h"
 #include "base/strings/sys_string_conversions.h"
 #include "ios/chrome/browser/browser_state/chrome_browser_state.h"
 #include "ios/chrome/browser/browser_state/test_chrome_browser_state.h"
 #include "ios/chrome/browser/crash_report/crash_restore_helper.h"
 #import "ios/chrome/browser/sessions/session_service.h"
 #include "ios/web/public/test/test_web_thread_bundle.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/platform_test.h"
 #import "third_party/ocmock/OCMock/OCMock.h"
 #include "third_party/ocmock/gtest_support.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 using testing::Return;
 
 @interface CrashRestoreHelper (Test)
 - (NSString*)sessionBackupPath;
 @end
 
 namespace {
 
 class CrashRestoreHelperTest : public PlatformTest {
  public:
   void SetUp() override {
     TestChromeBrowserState::Builder test_cbs_builder;
     chrome_browser_state_ = test_cbs_builder.Build();
     otr_chrome_browser_state_ =
         chrome_browser_state_->GetOffTheRecordChromeBrowserState();
-    helper_.reset([[CrashRestoreHelper alloc]
-        initWithBrowserState:chrome_browser_state_.get()]);
+    helper_ = [[CrashRestoreHelper alloc]
+        initWithBrowserState:chrome_browser_state_.get()];
   }
 
  protected:
   web::TestWebThreadBundle thread_bundle_;
   std::unique_ptr<TestChromeBrowserState> chrome_browser_state_;
   ios::ChromeBrowserState* otr_chrome_browser_state_;
-  base::scoped_nsobject<CrashRestoreHelper> helper_;
+  CrashRestoreHelper* helper_;
 };
 
 TEST_F(CrashRestoreHelperTest, MoveAsideTest) {
   NSString* backupPath = [helper_ sessionBackupPath];
   NSFileManager* fileManager = [NSFileManager defaultManager];
   [fileManager removeItemAtPath:backupPath error:NULL];
 
   NSData* data = [NSData dataWithBytes:"hello" length:5];
   SessionServiceIOS* sessionService = [SessionServiceIOS sharedService];
   NSString* profileStashPath =
       base::SysUTF8ToNSString(chrome_browser_state_->GetStatePath().value());
   NSString* sessionPath =
       [sessionService sessionFilePathForDirectory:profileStashPath];
   [fileManager createFileAtPath:sessionPath contents:data attributes:nil];
   NSString* otrProfileStashPath = base::SysUTF8ToNSString(
       otr_chrome_browser_state_->GetStatePath().value());
   NSString* otrSessionPath =
       [sessionService sessionFilePathForDirectory:otrProfileStashPath];
   [fileManager createFileAtPath:otrSessionPath contents:data attributes:nil];
 
   [helper_ moveAsideSessionInformation];
 
   EXPECT_EQ(NO, [fileManager fileExistsAtPath:sessionPath]);
   EXPECT_EQ(NO, [fileManager fileExistsAtPath:otrSessionPath]);
   EXPECT_EQ(YES, [fileManager fileExistsAtPath:backupPath]);
   [fileManager removeItemAtPath:backupPath error:NULL];
 }
 
 }  // namespace