[Thumbnails DB] Add functionality to clear unused on-demand favicons.

components/history/core/browser/thumbnail_database.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_HISTORY_CORE_BROWSER_THUMBNAIL_DATABASE_H_
 #define COMPONENTS_HISTORY_CORE_BROWSER_THUMBNAIL_DATABASE_H_
 
 #include <vector>
 
 #include "base/gtest_prod_util.h"
@@ skipping 48 matching lines @@
   void RollbackTransaction();
 
   // Vacuums the database. This will cause sqlite to defragment and collect
   // unused space in the file. It can be VERY SLOW.
   void Vacuum();
 
   // Try to trim the cache memory used by the database.  If |aggressively| is
   // true try to trim all unused cache, otherwise trim by half.
   void TrimMemory(bool aggressively);
 
+  // Get all on-demand favicon bitmaps that have been last requested prior to
+  // |threshold|.
+  std::map<favicon_base::FaviconID, IconMappingsForExpiry>
+  GetOldOnDemandFavicons(base::Time threshold);
+
   // Favicon Bitmaps -----------------------------------------------------------
 
   // Returns true if there are favicon bitmaps for |icon_id|. If
   // |bitmap_id_sizes| is non NULL, sets it to a list of the favicon bitmap ids
   // and their associated pixel sizes for the favicon with |icon_id|.
   // The list contains results for the bitmaps which are cached in the
   // favicon_bitmaps table. The pixel sizes are a subset of the sizes in the
   // 'sizes' field of the favicons table for |icon_id|.
   bool GetFaviconBitmapIDSizes(
       favicon_base::FaviconID icon_id,
@@ skipping 114 matching lines @@
 
   // Adds a mapping between the given page_url and icon_id.
   // Returns the new mapping id if the adding succeeds, otherwise 0 is returned.
   IconMappingID AddIconMapping(const GURL& page_url,
                                favicon_base::FaviconID icon_id);
 
   // Deletes the icon mapping entries for the given page url.
   // Returns true if the deletion succeeded.
   bool DeleteIconMappings(const GURL& page_url);
 
+  // Deletes the icon mapping entries for the given favicon ID.
+  // Returns true if the deletion succeeded.
+  bool DeleteIconMappingsForFaviconId(favicon_base::FaviconID id);
+
   // Deletes the icon mapping with |mapping_id|.
   // Returns true if the deletion succeeded.
   bool DeleteIconMapping(IconMappingID mapping_id);
 
   // Checks whether a favicon is used by any URLs in the database.
   bool HasMappingFor(favicon_base::FaviconID id);
 
   // The class to enumerate icon mappings. Use InitIconMappingEnumerator to
   // initialize.
   class IconMappingEnumerator {
@@ skipping 64 matching lines @@
 
   sql::Connection db_;
   sql::MetaTable meta_table_;
 
   HistoryBackendClient* backend_client_;
 };
 
 }  // namespace history
 
 #endif  // COMPONENTS_HISTORY_CORE_BROWSER_THUMBNAIL_DATABASE_H_