Make sql::Connection::Raze() more robust against corruptions.

sql/connection_unittest.cc

Index: sql/connection_unittest.cc
diff --git a/sql/connection_unittest.cc b/sql/connection_unittest.cc
index e50043fa940e731b9fe9dde503f5757cc60a2642..80364096133df84d6757b394e33a8a4a383b3792 100644
--- a/sql/connection_unittest.cc
+++ b/sql/connection_unittest.cc
@@ -186,7 +186,7 @@ TEST_F(SQLConnectionTest, Raze) {
   {
     sql::Statement s(db().GetUniqueStatement("PRAGMA auto_vacuum"));
     ASSERT_TRUE(s.Step());
-    // auto_vacuum must be preserved across a Raze.
+    // The new database has the same auto_vacuum as a fresh database.
     EXPECT_EQ(pragma_auto_vacuum, s.ColumnInt(0));
   }
 }