Adding last_forced column to thumbnails database.

chrome/browser/history/top_sites_database.h

Index: chrome/browser/history/top_sites_database.h
diff --git a/chrome/browser/history/top_sites_database.h b/chrome/browser/history/top_sites_database.h
index 053f03b0585f63ad5cbd1a380ce65e10edff4e17..e1df910c721497d9a6ef459320834408de994138 100644
--- a/chrome/browser/history/top_sites_database.h
+++ b/chrome/browser/history/top_sites_database.h
@@ -60,6 +60,15 @@ class TopSitesDatabase {
  private:
   FRIEND_TEST_ALL_PREFIXES(TopSitesDatabaseTest, Version1);
   FRIEND_TEST_ALL_PREFIXES(TopSitesDatabaseTest, Version2);
+  FRIEND_TEST_ALL_PREFIXES(TopSitesDatabaseTest, Version3);
+  FRIEND_TEST_ALL_PREFIXES(TopSitesDatabaseTest, AddRemoveEditThumbnails);
+
+  // Rank of all URLs that are forced and therefore cannot be automatically
+  // evicted.
+  static const int kRankOfForcedURL = -1;
+
+  // Rank used to indicate that a URL is not stored in the database.
+  static const int kRankOfNonExistingURL = -2;
 
   // Creates the thumbnail table, returning true if the table already exists
   // or was successfully created.
@@ -69,6 +78,10 @@ class TopSitesDatabase {
   // upgrade was successful.
   bool UpgradeToVersion2();
 
+  // Upgrades the thumbnail table to version 3, returning true if the
+  // upgrade was successful.
+  bool UpgradeToVersion3();
+
   // Adds a new URL to the database.
   void AddPageThumbnail(const MostVisitedURL& url,
                         int new_rank,
@@ -82,12 +95,9 @@ class TopSitesDatabase {
   bool UpdatePageThumbnail(const MostVisitedURL& url,
                            const Images& thumbnail);
 
-  // Returns the URL's current rank or -1 if it is not present.
+  // Returns |url|'s current rank or kRankOfNonExistingURL if not present.
   int GetURLRank(const MostVisitedURL& url);
 
-  // Returns the number of URLs (rows) in the database.
-  int GetRowCount();
-
   sql::Connection* CreateDB(const base::FilePath& db_name);
 
   // Encodes redirects into a string.