Implement WebStorageArea::containsItem(key) in chrome and drt/test_shell.

webkit/dom_storage/dom_storage_map.h

 // 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.
 
 #ifndef WEBKIT_DOM_STORAGE_DOM_STORAGE_MAP_H_
 #define WEBKIT_DOM_STORAGE_DOM_STORAGE_MAP_H_
 #pragma once
 
 #include <map>
 
 #include "base/memory/ref_counted.h"
 #include "base/nullable_string16.h"
 #include "base/string16.h"
 #include "webkit/dom_storage/dom_storage_types.h"
 
 namespace dom_storage {
 
 // A wrapper around a std::map that adds refcounting and
 // tracks the size in bytes of the keys/values, enforcing a quota.
 // See class comments for DomStorageContext for a larger overview.
 class DomStorageMap
     : public base::RefCountedThreadSafe<DomStorageMap> {
  public:
   explicit DomStorageMap(size_t quota);
 
   unsigned Length() const;
   NullableString16 Key(unsigned index);
   NullableString16 GetItem(const string16& key) const;
+  bool ContainsItem(const string16& key) const;
   bool SetItem(const string16& key, const string16& value,
                NullableString16* old_value);
   bool RemoveItem(const string16& key, string16* old_value);
 
   // Swaps this instances values_ with |map|.
   // Note: to grandfather in pre-existing files that are overbudget,
   // this method does not do quota checking.
   void SwapValues(ValuesMap* map);
 
   // Writes a copy of the current set of values_ to the |map|.
@@ skipping 16 matching lines @@
   ValuesMap values_;
   ValuesMap::const_iterator key_iterator_;
   unsigned last_key_index_;
   size_t bytes_used_;
   size_t quota_;
 };
 
 }  // namespace dom_storage
 
 #endif  // WEBKIT_DOM_STORAGE_DOM_STORAGE_MAP_H_