linux_aura: Fix crash when dragging NTP icons.

ui/base/x/selection_utils.cc

 // Copyright (c) 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 "ui/base/x/selection_utils.h"
 
 #include <set>
 
 #include "base/i18n/icu_string_conversions.h"
 #include "base/logging.h"
@@ skipping 86 matching lines @@
 
 ///////////////////////////////////////////////////////////////////////////////
 
 SelectionFormatMap::SelectionFormatMap() {}
 
 SelectionFormatMap::~SelectionFormatMap() {}
 
 void SelectionFormatMap::Insert(
     ::Atom atom,
     const scoped_refptr<base::RefCountedMemory>& item) {
+  data_.erase(atom);
   data_.insert(std::make_pair(atom, item));
 }
 
 ui::SelectionData SelectionFormatMap::GetFirstOf(
     const std::vector< ::Atom>& requested_types) const {
   for (std::vector< ::Atom>::const_iterator it = requested_types.begin();
        it != requested_types.end(); ++it) {
     const_iterator data_it = data_.find(*it);
     if (data_it != data_.end()) {
       return SelectionData(data_it->first, data_it->second);
@@ skipping 106 matching lines @@
 
 void SelectionData::AssignTo(std::string* result) const {
   *result = RefCountedMemoryToString(memory_);
 }
 
 void SelectionData::AssignTo(string16* result) const {
   *result = RefCountedMemoryToString16(memory_);
 }
 
 }  // namespace ui