Cleanup: Pass std::string as const reference from content/

content/renderer/history_entry.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.
 
 /*
  * Copyright (C) 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  *     (http://www.torchmobile.com/)
  *
@@ skipping 99 matching lines @@
     : entry_(entry) {
   if (!item.isNull())
     set_item(item);
   children_.reset(new ScopedVector<HistoryNode>);
 }
 
 HistoryEntry::HistoryNode::~HistoryNode() {
   if (!entry_ || item_.isNull())
     return;
 
-  for (std::string name : unique_names_) {
+  for (const std::string& name : unique_names_) {
     if (entry_->unique_names_to_items_[name] == this)
       entry_->unique_names_to_items_.erase(name);
   }
 }
 
 void HistoryEntry::HistoryNode::RemoveChildren() {
   children_.reset(new ScopedVector<HistoryNode>);
 }
 
 HistoryEntry::HistoryEntry() : weak_ptr_factory_(this) {
@@ skipping 28 matching lines @@
   return unique_names_to_items_[frame->GetWebFrame()->uniqueName().utf8()];
 }
 
 WebHistoryItem HistoryEntry::GetItemForFrame(RenderFrameImpl* frame) {
   if (HistoryNode* history_node = GetHistoryNodeForFrame(frame))
     return history_node->item();
   return WebHistoryItem();
 }
 
 }  // namespace content