[build-fix] [gcc 4.6.*] Use iterator instead of const_iterator while using std::map::erase(...)

mojo/services/window_manager/window_manager_app.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 "mojo/services/window_manager/window_manager_app.h"
 
 #include "base/message_loop/message_loop.h"
 #include "base/stl_util.h"
 #include "mojo/aura/aura_init.h"
 #include "mojo/aura/window_tree_host_mojo.h"
@@ skipping 243 matching lines @@
   window->SetProperty(kNodeKey, node);
   parent->AddChild(window);
   node_id_to_window_map_[id] = window;
   view_manager::Node::Children::const_iterator it = node->children().begin();
   for (; it != node->children().end(); ++it)
     RegisterSubtree((*it)->id(), window);
 }
 
 void WindowManagerApp::UnregisterSubtree(view_manager::Id id) {
   view_manager::Node* node = view_manager_->GetNodeById(id);
-  NodeIdToWindowMap::const_iterator it = node_id_to_window_map_.find(id);
+  NodeIdToWindowMap::iterator it = node_id_to_window_map_.find(id);
   DCHECK(it != node_id_to_window_map_.end());
   scoped_ptr<aura::Window> window(it->second);
   node_id_to_window_map_.erase(it);
   view_manager::Node::Children::const_iterator child = node->children().begin();
   for (; child != node->children().end(); ++child)
     UnregisterSubtree((*child)->id());
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // ApplicationDelegate, public:
 
 // static
 ApplicationDelegate* ApplicationDelegate::Create() {
   return new WindowManagerApp;
 }
 
 }  // namespace mojo