Hook up DomStorageArea with a DomStorageDatabase.

webkit/dom_storage/dom_storage_database.cc

 // 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.
 
 #include "webkit/dom_storage/dom_storage_database.h"
 
 #include "base/file_util.h"
 #include "base/logging.h"
 #include "sql/diagnostic_error_delegate.h"
 #include "sql/statement.h"
@@ skipping 22 matching lines @@
       tried_to_recreate_(false) {
   // Note: in normal use we should never get an empty backing path here.
   // However, the unit test for this class defines another constructor
   // that will bypass this check to allow an empty path that signifies
   // we should operate on an in-memory database for performance/reliability
   // reasons.
   DCHECK(!file_path_.empty());
 }
 
 DomStorageDatabase::~DomStorageDatabase() {
+  if (IsOpen()) {
+    sql::Statement statement(db_->GetCachedStatement(SQL_FROM_HERE,
+        "SELECT COUNT(key) from ItemTable"));

[michaeln, 2012/02/23 20:48:48]

like we chatted about, can the 'its empty' condition be determined w/o incurring
disk io at dtor time... probably worth some extra statefullness in this class to
avoid many small bits of io at browser shutdown

[benm (inactive), 2012/02/24 12:42:01]

Done, but moved to it's own CL in http://codereview.chromium.org/9467003/

+    if (statement.Step() && statement.ColumnInt(0) == 0) {
+      // Delete the db from disk, it's empty.
+      statement.Clear();
+      Close();
+      file_util::Delete(file_path_, false);
+    }
+  }
 }
 
 void DomStorageDatabase::ReadAllValues(ValuesMap* result) {
   if (!LazyOpen(false))
     return;
 
   sql::Statement statement(db_->GetCachedStatement(SQL_FROM_HERE,
                                                    "SELECT * from ItemTable"));
   DCHECK(statement.is_valid());
 
@@ skipping 198 matching lines @@
       CreateTableV2() &&
       CommitChanges(false, values) &&
       migration.Commit();
 }
 
 void DomStorageDatabase::Close() {
   db_.reset(NULL);
 }
 
 }  // namespace dom_storage