Use container::back() and container::pop_back() for content.

content/child/indexed_db/webidbcursor_impl.cc

 // Copyright 2013 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 "content/child/indexed_db/webidbcursor_impl.h"
 
 #include <stddef.h>
 
 #include <string>
 #include <vector>
@@ skipping 168 matching lines @@
   }
 
   callbacks->onSuccess(WebIDBKeyBuilder::Build(key),
                        WebIDBKeyBuilder::Build(primary_key), value);
 }
 
 void WebIDBCursorImpl::ResetPrefetchCache() {
   continue_count_ = 0;
   prefetch_amount_ = kMinPrefetchAmount;
 
-  if (!prefetch_keys_.size()) {
+  if (prefetch_keys_.empty()) {
     // No prefetch cache, so no need to reset the cursor in the back-end.
     return;
   }
 
   // Ack any unused blobs.
   std::vector<std::string> uuids;
   for (const auto& value : prefetch_values_) {
     for (size_t i = 0, size = value.webBlobInfo.size(); i < size; ++i)
       uuids.push_back(value.webBlobInfo[i].uuid().latin1());
   }
   if (!uuids.empty())
     thread_safe_sender_->Send(new IndexedDBHostMsg_AckReceivedBlobs(uuids));
 
   // Reset the back-end cursor.
   IndexedDBDispatcher* dispatcher =
       IndexedDBDispatcher::ThreadSpecificInstance(thread_safe_sender_.get());
   dispatcher->RequestIDBCursorPrefetchReset(
       used_prefetches_, prefetch_keys_.size(), ipc_cursor_id_);
 
   // Reset the prefetch cache.
   prefetch_keys_.clear();
   prefetch_primary_keys_.clear();
   prefetch_values_.clear();
 
   pending_onsuccess_callbacks_ = 0;
 }
 
 }  // namespace content