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

ios/web/public/web_thread.h

 // Copyright 2014 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_WEB_PUBLIC_WEB_THREAD_H_
 #define IOS_WEB_PUBLIC_WEB_THREAD_H_
 
 #include <string>
 
 #include "base/callback_forward.h"
@@ skipping 199 matching lines @@
   // unregistered by providing a nullptr pointer.
   //
   // If the caller unregisters a delegate before CleanUp has been
   // called, it must perform its own locking to ensure the delegate is
   // not deleted while unregistering.
   static void SetDelegate(ID identifier, WebThreadDelegate* delegate);
 
   // Returns an appropriate error message for when DCHECK_CURRENTLY_ON() fails.
   static std::string GetDCheckCurrentlyOnErrorMessage(ID expected);
 
-  // Use these templates in conjunction with RefCountedThreadSafe or scoped_ptr
-  // when you want to ensure that an object is deleted on a specific thread.
-  // This is needed when an object can hop between threads
+  // Use these templates in conjunction with RefCountedThreadSafe or
+  // std::unique_ptr when you want to ensure that an object is deleted on a
+  // specific thread. This is needed when an object can hop between threads
   // (i.e. IO -> FILE -> IO), and thread switching delays can mean that the
   // final IO tasks executes before the FILE task's stack unwinds.
   // This would lead to the object destructing on the FILE thread, which often
   // is not what you want (i.e. to unregister from NotificationService, to
   // notify other objects on the creating thread etc).
   template <ID thread>
   struct DeleteOnThread {
     template <typename T>
     static void Destruct(const T* x) {
       if (CurrentlyOn(thread)) {
@@ skipping 17 matching lines @@
   //     : public base::RefCountedThreadSafe<
   //           Foo, web::WebThread::DeleteOnIOThread> {
   //
   // ...
   //  private:
   //   friend struct web::WebThread::DeleteOnThread<web::WebThread::IO>;
   //   friend class base::DeleteHelper<Foo>;
   //
   //   ~Foo();
   //
-  // Sample usage with scoped_ptr:
-  // scoped_ptr<Foo, web::WebThread::DeleteOnIOThread> ptr;
+  // Sample usage with std::unique_ptr:
+  // std::unique_ptr<Foo, web::WebThread::DeleteOnIOThread> ptr;
   struct DeleteOnUIThread : public DeleteOnThread<UI> {};
   struct DeleteOnIOThread : public DeleteOnThread<IO> {};
   struct DeleteOnFileThread : public DeleteOnThread<FILE> {};
   struct DeleteOnDBThread : public DeleteOnThread<DB> {};
 
  private:
   friend class WebThreadImpl;
 
   WebThread() {}
   DISALLOW_COPY_AND_ASSIGN(WebThread);
 };
 
 }  // namespace web
 
 #endif  // IOS_WEB_PUBLIC_WEB_THREAD_H_