Some history backend fixes for database corruption.

chrome/browser/history/visit_database.cc

 // Copyright (c) 2006-2008 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.
 
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <set>
 
 #include "chrome/browser/history/visit_database.h"
@@ skipping 141 matching lines @@
       "SELECT" HISTORY_VISIT_ROW_FIELDS "FROM visits WHERE id=?");
   if (!statement.is_valid())
     return false;
 
   statement->bind_int64(0, visit_id);
   AddEventToVisitLog(VisitLog::SELECT_VISIT);
   if (statement->step() != SQLITE_ROW)
     return false;
 
   FillVisitRow(*statement, out_visit);
+
+  // We got a different visit than we asked for, something is wrong.
+  DCHECK_EQ(visit_id, out_visit->visit_id);
+  if (visit_id != out_visit->visit_id)
+    return false;
+
   return true;
 }
 
 bool VisitDatabase::UpdateVisitRow(const VisitRow& visit) {
+  // Don't store inconsistent data to the database.
+  DCHECK_NE(visit.visit_id, visit.referring_visit);
+  if (visit.visit_id == visit.referring_visit)
+    return false;
+
   SQLITE_UNIQUE_STATEMENT(statement, GetStatementCache(),
       "UPDATE visits SET "
       "url=?,visit_time=?,from_visit=?,transition=?,segment_id=?,is_indexed=? "
       "WHERE id=?");
   if (!statement.is_valid())
     return false;
 
   statement->bind_int64(0, visit.url_id);
   statement->bind_int64(1, visit.visit_time.ToInternalValue());
   statement->bind_int64(2, visit.referring_visit);
@@ skipping 270 matching lines @@
   if (!statement.is_valid() || statement->step() != SQLITE_ROW ||
       statement->column_int64(0) == 0) {
     *first_visit = Time::Now();
     return false;
   }
   *first_visit = Time::FromInternalValue(statement->column_int64(0));
   return true;
 }
 
 }  // namespace history