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

ios/chrome/browser/snapshots/lru_cache.mm

 // 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.
 
 #import "ios/chrome/browser/snapshots/lru_cache.h"
 
 #include <stddef.h>
 
+#include <memory>
+
 #include "base/containers/hash_tables.h"
 #include "base/containers/mru_cache.h"
 #include "base/mac/scoped_nsobject.h"
 #include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
 
 namespace {
 
 struct NSObjectEqualTo {
   bool operator()(const base::scoped_nsprotocol<id<NSObject>>& obj1,
                   const base::scoped_nsprotocol<id<NSObject>>& obj2) const {
     return [obj1 isEqual:obj2];
   }
 };
 
@@ skipping 25 matching lines @@
   explicit NSObjectMRUCache(typename ParentType::size_type max_size)
       : ParentType(max_size) {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(NSObjectMRUCache);
 };
 
 }  // namespace
 
 @implementation LRUCache {
-  scoped_ptr<NSObjectMRUCache> _cache;
+  std::unique_ptr<NSObjectMRUCache> _cache;
 }
 
 @synthesize maxCacheSize = _maxCacheSize;
 
 - (instancetype)init {
   NOTREACHED();  // Use initWithCacheSize: instead.
   return nil;
 }
 
 - (instancetype)initWithCacheSize:(NSUInteger)maxCacheSize {
@@ skipping 32 matching lines @@
 
 - (NSUInteger)count {
   return _cache->size();
 }
 
 - (BOOL)isEmpty {
   return _cache->empty();
 }
 
 @end