components: Cleanup class/struct fwd declarations

components/omnibox/browser/url_index_private_data.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 COMPONENTS_OMNIBOX_BROWSER_URL_INDEX_PRIVATE_DATA_H_
 #define COMPONENTS_OMNIBOX_BROWSER_URL_INDEX_PRIVATE_DATA_H_
 
 #include <stddef.h>
 
 #include <set>
@@ skipping 14 matching lines @@
 class BookmarkModel;
 }
 
 namespace in_memory_url_index {
 class InMemoryURLIndexCacheItem;
 }
 
 namespace history {
 class HistoryDatabase;
 class InMemoryURLIndex;
-class RefCountedBool;
 }
 
 // Current version of the cache file.
 static const int kCurrentCacheFileVersion = 5;
 
 // A structure private to InMemoryURLIndex describing its internal data and
 // providing for restoring, rebuilding and updating that internal data. As
 // this class is for exclusive use by the InMemoryURLIndex class there should
 // be no calls from any other class.
 //
@@ skipping 336 matching lines @@
   int saved_cache_version_;
 
   // Used for unit testing only. Records the number of candidate history items
   // at three stages in the index searching process.
   size_t pre_filter_item_count_;    // After word index is queried.
   size_t post_filter_item_count_;   // After trimming large result set.
   size_t post_scoring_item_count_;  // After performing final filter/scoring.
 };
 
 #endif  // COMPONENTS_OMNIBOX_BROWSER_URL_INDEX_PRIVATE_DATA_H_