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

ios/chrome/browser/tab_parenting_global_observer.h

 // 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.
 
 #ifndef IOS_CHROME_BROWSER_TAB_PARENTING_GLOBAL_OBSERVER_H_
 #define IOS_CHROME_BROWSER_TAB_PARENTING_GLOBAL_OBSERVER_H_
 
+#include <memory>
+
 #include "base/callback_list.h"
 #include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
 
 namespace base {
 template <typename T>
 struct DefaultSingletonTraits;
 }  // namespace base
 
 namespace web {
 class WebState;
 }
 
 // Allows clients to observe every tab (i.e., WebState) that is parented.
 // NOTE: Should be used only to correspond to //chrome flows that listen for
 // the TAB_PARENTED notification from all sources.
 class TabParentingGlobalObserver {
  public:
   typedef base::Callback<void(web::WebState*)> OnTabParentedCallback;
 
   // Returns the instance of TabParentingGlobalObserver.
   static TabParentingGlobalObserver* GetInstance();
 
   // Registers |cb| to be invoked when a tab is parented.
-  scoped_ptr<base::CallbackList<void(web::WebState*)>::Subscription>
+  std::unique_ptr<base::CallbackList<void(web::WebState*)>::Subscription>
   RegisterCallback(const OnTabParentedCallback& cb);
 
   // Called to notify all registered callbacks that |web_state| was parented.
   void OnTabParented(web::WebState* web_state);
 
  private:
   friend struct base::DefaultSingletonTraits<TabParentingGlobalObserver>;
 
   TabParentingGlobalObserver();
   ~TabParentingGlobalObserver();
 
   base::CallbackList<void(web::WebState*)> on_tab_parented_callback_list_;
 
   DISALLOW_COPY_AND_ASSIGN(TabParentingGlobalObserver);
 };
 
 #endif  // IOS_CHROME_BROWSER_TAB_PARENTING_GLOBAL_OBSERVER_H_