1. Create and use the TopSites database file....

chrome/browser/history/top_sites_database.h

 // Copyright (c) 2010 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 CHROME_BROWSER_HISTORY_TOP_SITES_DATABASE_H_
 #define CHROME_BROWSER_HISTORY_TOP_SITES_DATABASE_H_
 
 #include <string>
 #include <vector>
 
 #include "app/sql/connection.h"
-#include "app/sql/init_status.h"
-#include "app/sql/meta_table.h"
 #include "base/ref_counted.h"
 #include "chrome/browser/history/history_types.h"
 #include "chrome/browser/history/url_database.h"  // For DBCloseScoper.
 
 class FilePath;
 class RefCountedMemory;
 class SkBitmap;
 class TopSites;
 
 namespace base {
 class Time;
 }
 
 namespace history {
 
 // Interface to be implemented by the real storage layer as well as
 // the mockup database for testing.
 class TopSitesDatabase {
  public:
   virtual ~TopSitesDatabase() {}
+  virtual bool Init(const FilePath& filename) {
+    return true;
+  }
 
   // Returns a list of all URLs currently in the table.
   virtual MostVisitedURLList GetTopURLs() = 0;
 
   // Set a thumbnail for a URL. |url_rank| is the position of the URL
   // in the list of TopURLs, zero-based.
   // If the URL is not in the table, add it. If it is, replace its
   // thumbnail.
   virtual void SetPageThumbnail(const MostVisitedURL& url,
                                 int url_rank,
                                 const TopSites::Images& thumbnail) = 0;
 
   // Get a thumbnail for a given page. Returns true iff we have the thumbnail.
   virtual bool GetPageThumbnail(const MostVisitedURL& url,
                                 TopSites::Images* thumbnail) = 0;
 
   // Remove the record for this URL. Returns true iff removed successfully.
   virtual bool RemoveURL(const MostVisitedURL& url) = 0;
 };
 
-class TopSitesDatabaseImpl: public TopSitesDatabase {
+class TopSitesDatabaseImpl : public TopSitesDatabase {
  public:
   TopSitesDatabaseImpl();
   ~TopSitesDatabaseImpl() {}
 
   // Must be called after creation but before any other methods are called.
   // Returns true on success. If false, no other functions should be called.
-  bool Init(const FilePath& db_name);
+  virtual bool Init(const FilePath& db_name);
 
   // Thumbnails ----------------------------------------------------------------
 
   // Returns a list of all URLs currently in the table.
   virtual MostVisitedURLList GetTopURLs();
 
   // Set a thumbnail for a URL. |url_rank| is the position of the URL
   // in the list of TopURLs, zero-based.
   // If the URL is not in the table, add it. If it is, replace its
   // thumbnail and rank. Shift the ranks of other URLs if necessary.
@@ skipping 27 matching lines @@
 
   // Decodes redirects from a string and sets them for the url.
   static void SetRedirects(const std::string& redirects, MostVisitedURL* url);
 
   sql::Connection db_;
 };
 
 }  // namespace history
 
 #endif  // CHROME_BROWSER_HISTORY_TOP_SITES_DATABASE_H_