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

components/history/core/browser/thumbnail_database.cc

Index: components/history/core/browser/thumbnail_database.cc
diff --git a/components/history/core/browser/thumbnail_database.cc b/components/history/core/browser/thumbnail_database.cc
index c8b430f4f71d8dd70f0111995c5ce74297cec7d9..d452bd5d744595f3d31a216c2b63d984e381be61 100644
--- a/components/history/core/browser/thumbnail_database.cc
+++ b/components/history/core/browser/thumbnail_database.cc
@@ -412,11 +412,42 @@ void ThumbnailDatabase::TrimMemory(bool aggressively) {
   db_.TrimMemory(aggressively);
 }
 
+std::map<favicon_base::FaviconID, IconMappingsForExpiry>
+ThumbnailDatabase::GetOldOnDemandFavicons(base::Time threshold) {
+  // Restrict to on-demand bitmaps (i.e. with last_requested != 0). This is
+  // called rarely during history expiration cleanup and hence not worth
+  // caching.
+  // TODO(jkrcal): In M63, remove the "(last_requested=0 AND last_updated=0)"
+  // clause which is only transitional - to clean up expired icons (previously,
+  // on-demand favicons were stored as expired on-visit favicons).
+  sql::Statement old_icons(db_.GetUniqueStatement(
+      "SELECT favicons.id, favicons.url, icon_mapping.page_url "
+      "FROM favicons "
+      "JOIN favicon_bitmaps ON (favicon_bitmaps.icon_id = favicons.id) "
+      "JOIN icon_mapping ON (icon_mapping.icon_id = favicon_bitmaps.icon_id) "
+      "WHERE ((favicon_bitmaps.last_requested = 0 AND "
+      "        favicon_bitmaps.last_updated = 0) OR "
+      "       (favicon_bitmaps.last_requested > 0 AND "
+      "        favicon_bitmaps.last_requested < ?))"));
+  old_icons.BindInt64(0, threshold.ToInternalValue());

[jkrcal, 2017/07/25 13:40:17]

I've ignored a presubmit warning to avoid deprecated Time::ToInternalValue(). To
me, it makes sense to replace all instances in this file in one CL so that it
stays consistent.

+
+  std::map<favicon_base::FaviconID, IconMappingsForExpiry> icon_mappings;
+
+  while (old_icons.Step()) {
+    favicon_base::FaviconID id = old_icons.ColumnInt64(0);
+    icon_mappings[id].icon_url = GURL(old_icons.ColumnString(1));
+    icon_mappings[id].page_urls.push_back(GURL(old_icons.ColumnString(2)));
+  }
+
+  return icon_mappings;
+}
+
 bool ThumbnailDatabase::GetFaviconBitmapIDSizes(
     favicon_base::FaviconID icon_id,
     std::vector<FaviconBitmapIDSize>* bitmap_id_sizes) {
   DCHECK(icon_id);
-  sql::Statement statement(db_.GetCachedStatement(SQL_FROM_HERE,
+  sql::Statement statement(db_.GetCachedStatement(
+      SQL_FROM_HERE,
       "SELECT id, width, height FROM favicon_bitmaps WHERE icon_id=?"));
   statement.BindInt64(0, icon_id);
 
@@ -778,6 +809,16 @@ bool ThumbnailDatabase::DeleteIconMappings(const GURL& page_url) {
   return statement.Run();
 }
 
+bool ThumbnailDatabase::DeleteIconMappingsForFaviconId(
+    favicon_base::FaviconID id) {
+  // This is called rarely during history expiration cleanup and hence not
+  // worth caching.
+  sql::Statement statement(
+      db_.GetUniqueStatement("DELETE FROM icon_mapping WHERE icon_id=?"));
+  statement.BindInt64(0, id);
+  return statement.Run();
+}
+
 bool ThumbnailDatabase::DeleteIconMapping(IconMappingID mapping_id) {
   sql::Statement statement(db_.GetCachedStatement(SQL_FROM_HERE,
       "DELETE FROM icon_mapping WHERE id=?"));