Revert 284958 "Make HistoryDBTask not refcounted, and ensure it'..."

trunk/src/chrome/browser/history/history_backend.h

Index: trunk/src/chrome/browser/history/history_backend.h
===================================================================
--- trunk/src/chrome/browser/history/history_backend.h	(revision 285001)
+++ trunk/src/chrome/browser/history/history_backend.h	(working copy)
@@ -51,26 +51,22 @@
 // the thumbnail database.
 static const size_t kMaxFaviconBitmapsPerIconURL = 8;
 
-// Keeps track of a queued HistoryDBTask. This class lives solely on the
-// DB thread.
 class QueuedHistoryDBTask {
  public:
   QueuedHistoryDBTask(
-      scoped_ptr<HistoryDBTask> task,
+      scoped_refptr<HistoryDBTask> task,
       scoped_refptr<base::SingleThreadTaskRunner> origin_loop,
       const base::CancelableTaskTracker::IsCanceledCallback& is_canceled);
   ~QueuedHistoryDBTask();
 
   bool is_canceled();
-  bool Run(HistoryBackend* backend, HistoryDatabase* db);
-  void DoneRun();
+  bool RunOnDBThread(HistoryBackend* backend, HistoryDatabase* db);
+  void DoneRunOnMainThread();
 
  private:
-  scoped_ptr<HistoryDBTask> task_;
+  scoped_refptr<HistoryDBTask> task_;
   scoped_refptr<base::SingleThreadTaskRunner> origin_loop_;
   base::CancelableTaskTracker::IsCanceledCallback is_canceled_;
-
-  DISALLOW_COPY_AND_ASSIGN(QueuedHistoryDBTask);
 };
 
 // *See the .cc file for more information on the design.*
@@ -377,7 +373,7 @@
   // Generic operations --------------------------------------------------------
 
   void ProcessDBTask(
-      scoped_ptr<HistoryDBTask> task,
+      scoped_refptr<HistoryDBTask> task,
       scoped_refptr<base::SingleThreadTaskRunner> origin_loop,
       const base::CancelableTaskTracker::IsCanceledCallback& is_canceled);
 
@@ -865,7 +861,7 @@
   bool segment_queried_;
 
   // List of QueuedHistoryDBTasks to run;
-  std::list<QueuedHistoryDBTask*> queued_history_db_tasks_;
+  std::list<QueuedHistoryDBTask> queued_history_db_tasks_;
 
   // Used to determine if a URL is bookmarked; may be NULL.
   //