Use std::default_delete as the default deleter for scoped_ptr.

components/invalidation/impl/mock_ack_handler.cc

 // 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.
 
 #include "components/invalidation/impl/mock_ack_handler.h"
 
+#include <algorithm>
+
 #include "base/thread_task_runner_handle.h"
 #include "components/invalidation/public/ack_handle.h"
 #include "components/invalidation/public/invalidation.h"
 
 namespace syncer {
 
 namespace {
 
 struct AckHandleMatcher {
   AckHandleMatcher(const AckHandle& handle);
@@ skipping 94 matching lines @@
       matcher);
   if (it != unacked_invalidations_.end()) {
     dropped_invalidations_.push_back(*it);
     unacked_invalidations_.erase(it);
   }
   unrecovered_drop_events_.erase(id);
   unrecovered_drop_events_.insert(std::make_pair(id, handle));
 }
 
 }  // namespace syncer