Convert //ios from scoped_ptr to std::unique_ptr.

ios/chrome/browser/installation_notifier_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 "ios/chrome/browser/installation_notifier.h"
 
 #include <stdint.h>
 #import <UIKit/UIKit.h>
 
 #include "base/ios/block_types.h"
@@ skipping 133 matching lines @@
                 50 + jitter * expectedDelayInMSec);
   }
 
   base::MessageLoopForUI message_loop_;
   web::TestWebThread ui_thread_;
   InstallationNotifier* installationNotifier_;  // Weak pointer to singleton.
   MockDispatcher* dispatcher_;  // Weak. installationNotifier_ owns it.
   base::scoped_nsobject<MockNotificationReceiver> notificationReceiver1_;
   base::scoped_nsobject<MockNotificationReceiver> notificationReceiver2_;
   base::scoped_nsobject<MockUIApplication> sharedApplication_;
-  scoped_ptr<base::HistogramTester> histogramTester_;
+  std::unique_ptr<base::HistogramTester> histogramTester_;
 };
 
 TEST_F(InstallationNotifierTest, RegisterWithAppAlreadyInstalled) {
   [sharedApplication_ setCanOpenURL:YES];
   [installationNotifier_
       registerForInstallationNotifications:notificationReceiver1_
                               withSelector:@selector(receivedNotification)
                                  forScheme:@"foo-scheme"];
   EXPECT_EQ(1, [notificationReceiver1_ notificationCount]);
   [installationNotifier_
@@ skipping 106 matching lines @@
 
 TEST_F(InstallationNotifierTest, TestThatEmptySchemeDoesntCrashChrome) {
   [installationNotifier_
       registerForInstallationNotifications:notificationReceiver1_
                               withSelector:@selector(receivedNotification)
                                  forScheme:nil];
   [installationNotifier_ unregisterForNotifications:notificationReceiver1_];
 }
 
 }  // namespace