Move TestingPrefService to use unique_ptr<Value>

ios/chrome/browser/ui/settings/utils/pref_backed_boolean_unittest.mm

 // Copyright 2016 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/ui/settings/utils/pref_backed_boolean.h"
 
+#include <utility>
+
+#include "base/memory/ptr_util.h"
 #include "base/values.h"
 #include "components/prefs/pref_registry_simple.h"
 #include "components/prefs/testing_pref_service.h"
 #import "ios/chrome/browser/ui/settings/utils/fake_observable_boolean.h"
 #include "ios/web/public/test/test_web_thread_bundle.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/platform_test.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 namespace {
 
 const char kTestSwitchPref[] = "test-pref";
 
 class PrefBackedBooleanTest : public PlatformTest {
  public:
   void SetUp() override {
     pref_service_.registry()->RegisterBooleanPref(kTestSwitchPref, false);
     observable_boolean_ =
         [[PrefBackedBoolean alloc] initWithPrefService:&pref_service_
                                               prefName:kTestSwitchPref];
   }
 
  protected:
   bool GetPref() { return pref_service_.GetBoolean(kTestSwitchPref); }
 
   void SetPref(bool value) {
-    base::Value* booleanValue = new base::Value(value);
-    pref_service_.SetUserPref(kTestSwitchPref, booleanValue);
+    auto booleanValue = base::MakeUnique<base::Value>(value);
+    pref_service_.SetUserPref(kTestSwitchPref, std::move(booleanValue));
   }
 
   PrefBackedBoolean* GetObservableBoolean() { return observable_boolean_; }
 
   web::TestWebThreadBundle thread_bundle_;
   TestingPrefServiceSimple pref_service_;
   PrefBackedBoolean* observable_boolean_;
 };
 
 TEST_F(PrefBackedBooleanTest, ReadFromPrefs) {
@@ skipping 20 matching lines @@
 
   SetPref(true);
   EXPECT_EQ(1, observer.updateCount) << "Changing value should update observer";
 
   SetPref(true);
   EXPECT_EQ(1, observer.updateCount)
       << "Setting the same value should not update observer";
 }
 
 }  // namespace