Convert //sync from scoped_ptr to std::unique_ptr

sync/internal_api/public/util/immutable.h

 // Copyright (c) 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.
 
 // Immutable<T> provides an easy, cheap, and thread-safe way to pass
 // large immutable data around.
 //
 // For example, consider the following code:
 //
 //  typedef std::vector<LargeObject> LargeObjectList;
@@ skipping 140 matching lines @@
 //   ----------
 //   #include ".../immutable.h"
 //
 //   // Forward declaration.
 //   class SomeOtherType;
 //
 //   class MyClass {
 //     ...
 //    private:
 //     struct ImmutableSomeOtherTypeTraits {
-//       // scoped_ptr<SomeOtherType> won't work here, either.
+//       // std::unique_ptr<SomeOtherType> won't work here, either.
 //       typedef SomeOtherType* Wrapper;
 //
 //       static void InitializeWrapper(Wrapper* wrapper);
 //
 //       static void DestroyWrapper(Wrapper* wrapper);
 //       ...
 //     };
 //
 //     typedef Immutable<SomeOtherType, ImmutableSomeOtherTypeTraits>
 //         ImmutableSomeOtherType;
@@ skipping 80 matching lines @@
 
 // Helper function to avoid having to write out template arguments.
 template <typename T>
 Immutable<T> MakeImmutable(T* t) {
   return Immutable<T>(t);
 }
 
 }  // namespace syncer
 
 #endif  // SYNC_INTERNAL_API_PUBLIC_UTIL_IMMUTABLE_H_