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

ios/chrome/browser/device_sharing/device_sharing_manager_unittest.mm

 // Copyright 2015 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/device_sharing/device_sharing_manager.h"
 
 #include <memory>
 
 #include "base/mac/foundation_util.h"
-#include "base/mac/scoped_nsobject.h"
 #import "components/handoff/handoff_manager.h"
 #include "components/handoff/pref_names_ios.h"
 #include "components/sync_preferences/testing_pref_service_syncable.h"
 #include "ios/chrome/browser/browser_state/test_chrome_browser_state.h"
 #include "ios/web/public/test/test_web_thread_bundle.h"
 #include "testing/platform_test.h"
 #import "third_party/ocmock/OCMock/OCMock.h"
 #import "third_party/ocmock/gtest_support.h"
 #include "url/gurl.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 @interface TestDeviceSharingManager : DeviceSharingManager
 + (HandoffManager*)createHandoffManager;
 @end
 
 @implementation TestDeviceSharingManager
 + (HandoffManager*)createHandoffManager {
   return [OCMockObject niceMockForClass:[HandoffManager class]];
 }
 @end
 
 namespace {
 
 class DeviceSharingManagerTest : public PlatformTest {
  protected:
   DeviceSharingManagerTest()
       : PlatformTest(),
         kTestURL1("http://test_sharing_1.html"),
         kTestURL2("http://test_sharing_2.html") {}
 
   void SetUp() override {
     PlatformTest::SetUp();
     TestChromeBrowserState::Builder mainBrowserStateBuilder;
     chrome_browser_state_ = mainBrowserStateBuilder.Build();
-    sharing_manager_.reset([[TestDeviceSharingManager alloc] init]);
+    sharing_manager_ = [[TestDeviceSharingManager alloc] init];
   }
 
   void TearDown() override {
     [sharing_manager_ updateBrowserState:NULL];
-    sharing_manager_.reset();
+    sharing_manager_ = nil;
   }
 
   const GURL kTestURL1;
   const GURL kTestURL2;
   web::TestWebThreadBundle thread_bundle_;
   std::unique_ptr<TestChromeBrowserState> chrome_browser_state_;
-  base::scoped_nsobject<DeviceSharingManager> sharing_manager_;
+  DeviceSharingManager* sharing_manager_;
 };
 
 TEST_F(DeviceSharingManagerTest, NoMainBrowserState) {
   EXPECT_FALSE([sharing_manager_ handoffManager]);
   // Updating the active URL should be a no-op.
   [sharing_manager_ updateActiveURL:GURL("http://test")];
   EXPECT_FALSE([sharing_manager_ handoffManager]);
 }
 
 TEST_F(DeviceSharingManagerTest, ShareOneUrl) {
@@ skipping 37 matching lines @@
 TEST_F(DeviceSharingManagerTest, DisableHandoffViaPrefs) {
   [sharing_manager_ updateBrowserState:chrome_browser_state_.get()];
   EXPECT_TRUE([sharing_manager_ handoffManager]);
   sync_preferences::TestingPrefServiceSyncable* prefs =
       chrome_browser_state_->GetTestingPrefService();
   prefs->SetBoolean(prefs::kIosHandoffToOtherDevices, false);
   EXPECT_FALSE([sharing_manager_ handoffManager]);
 }
 
 }  // namespace