Replace base::NullableString16(bool) usage with default constructor.

webkit/common/dom_storage/dom_storage_map.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 "webkit/common/dom_storage/dom_storage_map.h"
 
 #include "base/logging.h"
 
 namespace {
 
@@ skipping 23 matching lines @@
 }
 
 DomStorageMap::~DomStorageMap() {}
 
 unsigned DomStorageMap::Length() const {
   return values_.size();
 }
 
 base::NullableString16 DomStorageMap::Key(unsigned index) {
   if (index >= values_.size())
-    return base::NullableString16(true);
+    return base::NullableString16();
   while (last_key_index_ != index) {
     if (last_key_index_ > index) {
       --key_iterator_;
       --last_key_index_;
     } else {
       ++key_iterator_;
       ++last_key_index_;
     }
   }
   return base::NullableString16(key_iterator_->first, false);
 }
 
 base::NullableString16 DomStorageMap::GetItem(const base::string16& key) const {
   ValuesMap::const_iterator found = values_.find(key);
   if (found == values_.end())
-    return base::NullableString16(true);
+    return base::NullableString16();
   return found->second;
 }
 
 bool DomStorageMap::SetItem(
     const base::string16& key, const base::string16& value,
     base::NullableString16* old_value) {
   ValuesMap::const_iterator found = values_.find(key);
   if (found == values_.end())
-    *old_value = base::NullableString16(true);
+    *old_value = base::NullableString16();
   else
     *old_value = found->second;
 
   size_t old_item_size = old_value->is_null() ?
       0 : size_of_item(key, old_value->string());
   size_t new_item_size = size_of_item(key, value);
   size_t new_bytes_used = bytes_used_ - old_item_size + new_item_size;
 
   // Only check quota if the size is increasing, this allows
   // shrinking changes to pre-existing files that are over budget.
@@ skipping 33 matching lines @@
   copy->ResetKeyIterator();
   return copy;
 }
 
 void DomStorageMap::ResetKeyIterator() {
   key_iterator_ = values_.begin();
   last_key_index_ = 0;
 }
 
 }  // namespace dom_storage