Add PrerenderLocalPredictor, which will eventually perform

chrome/browser/history/history.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_HISTORY_H_
 #define CHROME_BROWSER_HISTORY_HISTORY_H_
 #pragma once
 
 #include <set>
 #include <vector>
@@ skipping 36 matching lines @@
 class InMemoryHistoryBackend;
 class InMemoryURLIndex;
 class InMemoryURLIndexTest;
 class HistoryAddPageArgs;
 class HistoryBackend;
 class HistoryDatabase;
 struct HistoryDetails;
 class HistoryQueryTest;
 class VisitFilter;
 class URLDatabase;
+class VisitDatabaseObserver;
 }  // namespace history
 
 
 // HistoryDBTask can be used to process arbitrary work on the history backend
 // thread. HistoryDBTask is scheduled using HistoryService::ScheduleDBTask.
 // When HistoryBackend processes the task it invokes RunOnDBThread. Once the
 // task completes and has not been canceled, DoneRunOnMainThread is invoked back
 // on the main thread.
 class HistoryDBTask : public base::RefCountedThreadSafe<HistoryDBTask> {
  public:
@@ skipping 474 matching lines @@
 
   // Schedules a HistoryDBTask for running on the history backend thread. See
   // HistoryDBTask for details on what this does.
   virtual void ScheduleDBTask(HistoryDBTask* task,
                               CancelableRequestConsumerBase* consumer);
 
   // Returns true if top sites needs to be migrated out of history into its own
   // db.
   bool needs_top_sites_migration() const { return needs_top_sites_migration_; }
 
+  // Adds or removes observers for the VisitDatabase.  Should be run in the
+  // thread in which the observer would like to be notified.
+  void AddVisitDatabaseObserver(history::VisitDatabaseObserver* observer);
+  void RemoveVisitDatabaseObserver(history::VisitDatabaseObserver* observer);
+
   // Testing -------------------------------------------------------------------
 
   // Designed for unit tests, this passes the given task on to the history
   // backend to be called once the history backend has terminated. This allows
   // callers to know when the history thread is complete and the database files
   // can be deleted and the next test run. Otherwise, the history thread may
   // still be running, causing problems in subsequent tests.
   //
   // There can be only one closing task, so this will override any previously
   // set task. We will take ownership of the pointer and delete it when done.
@@ skipping 336 matching lines @@
   // True if needs top site migration.
   bool needs_top_sites_migration_;
 
   // The index used for quick history lookups.
   scoped_ptr<history::InMemoryURLIndex> in_memory_url_index_;
 
   DISALLOW_COPY_AND_ASSIGN(HistoryService);
 };
 
 #endif  // CHROME_BROWSER_HISTORY_HISTORY_H_