Remove base's implicit_cast.

components/history/core/browser/history_backend.cc

 // 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.
 
 #include "components/history/core/browser/history_backend.h"
 
 #include <algorithm>
 #include <functional>
 #include <list>
 #include <map>
@@ skipping 1349 matching lines @@
   data.reserve(score_map.size());
   for (std::map<URLID, double>::iterator it = score_map.begin();
        it != score_map.end(); ++it) {
     PageUsageData* pud = new PageUsageData(it->first);
     pud->SetScore(it->second);
     data.push_back(pud);
   }
 
   // Limit to the top |result_count| results.
   std::sort(data.begin(), data.end(), PageUsageData::Predicate);
-  if (result_count && implicit_cast<int>(data.size()) > result_count)
+  DCHECK_GE(result_count, 0);
+  if (result_count && data.size() > static_cast<size_t>(result_count))
     data.resize(result_count);
 
   for (size_t i = 0; i < data.size(); ++i) {
     URLRow info;
     if (db_->GetURLRow(data[i]->GetID(), &info)) {
       data[i]->SetURL(info.url());
       data[i]->SetTitle(info.title());
     }
   }
 
@@ skipping 1316 matching lines @@
   // transaction is currently open.
   db_->CommitTransaction();
   db_->Vacuum();
   db_->BeginTransaction();
   db_->GetStartDate(&first_recorded_time_);
 
   return true;
 }
 
 }  // namespace history