Add PrerenderLocalPredictor, which will eventually perform

chrome/browser/history/visit_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 CHROME_BROWSER_HISTORY_VISIT_DATABASE_H_
 #define CHROME_BROWSER_HISTORY_VISIT_DATABASE_H_
 #pragma once
 
+#include "base/observer_list_threadsafe.h"
 #include "chrome/browser/history/history_types.h"
 
 namespace sql {
 class Connection;
 class Statement;
 }
 
 namespace history {
 
 class VisitFilter;
 
+// Abbreviated information about a visit.
+struct BriefVisitInfo {
+  URLID url_id;
+  base::Time time;
+  content::PageTransition transition;
+};
+
+// An observer of VisitDatabase.
+class VisitDatabaseObserver {

[cbentzel, 2012/04/17 20:28:16]

Should this handle DeleteVisit and UpdateVisit as well?

[tburkard, 2012/04/17 20:51:36]

I'm not concerned about these for now, the majority of operations is adding
visits.  We may add that later.

On 2012/04/17 20:28:16, cbentzel wrote:

+ public:
+  virtual ~VisitDatabaseObserver() {}
+  virtual void OnAddVisit(BriefVisitInfo info) = 0;

[cbentzel, 2012/04/17 20:28:16]

Why doesn't this take a const VisitRow& as an argument?

[tburkard, 2012/04/17 20:51:36]

Either would work.  I figured I'd use BriefVisitInfo since that was the
information I needed, so at the place where I'm using it, everything is
BriefVisitInfo's.

On 2012/04/17 20:28:16, cbentzel wrote:

[cbentzel, 2012/04/17 20:57:51]

Brett should make the call here - and OWNERS requires it :)

+};
+
 // A visit database is one which stores visits for URLs, that is, times and
 // linking information. A visit database must also be a URLDatabase, as this
 // modifies tables used by URLs directly and could be thought of as inheriting
 // from URLDatabase. However, this inheritance is not explicit as things would
 // get too complicated and have multiple inheritance.
 class VisitDatabase {
  public:
   // Must call InitVisitTable() before using to make sure the database is
   // initialized.
   VisitDatabase();
@@ skipping 135 matching lines @@
                                   int* count,
                                   base::Time* first_visit);
 
   // Get the time of the first item in our database.
   bool GetStartDate(base::Time* first_visit);
 
   // Get the source information about the given visits.
   void GetVisitsSource(const VisitVector& visits,
                        VisitSourceMap* sources);
 
+  // Adds or removes observers for the VisitDatabase.  Should be run on
+  // the thread in which the observer would like to be notified.
+  void AddVisitDatabaseObserver(VisitDatabaseObserver* observer);
+  void RemoveVisitDatabaseObserver(VisitDatabaseObserver* observer);
+
+  // Obtains BriefVisitInfo for the specified number of most recent visits
+  // from the visit database.
+  void GetBriefVisitInfoOfMostRecentVisits(
+      int max_visits,
+      std::vector<BriefVisitInfo>* result_vector);
+
  protected:
   // Returns the database for the functions in this interface.
   virtual sql::Connection& GetDB() = 0;
 
   // Called by the derived classes on initialization to make sure the tables
   // and indices are properly set up. Must be called before anything else.
   bool InitVisitTable();
 
   // Convenience to fill a VisitRow. Assumes the visit values are bound starting
   // at index 0.
   static void FillVisitRow(sql::Statement& statement, VisitRow* visit);
 
   // Convenience to fill a VisitVector. Assumes that statement.step()
   // hasn't happened yet.
   static bool FillVisitVector(sql::Statement& statement, VisitVector* visits);
 
   // Called by the derived classes to migrate the older visits table which
   // don't have visit_duration column yet.
   bool MigrateVisitsWithoutDuration();
 
  private:
+  scoped_refptr<ObserverListThreadSafe<VisitDatabaseObserver> > observers_;
 
   DISALLOW_COPY_AND_ASSIGN(VisitDatabase);
 };
 
 }  // history
 
 #endif  // CHROME_BROWSER_HISTORY_VISIT_DATABASE_H_