IDBObserver: Lifetime Management: Adding Observer

third_party/WebKit/Source/modules/indexeddb/IDBObserver.cpp

 // Copyright 2016 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 "modules/indexeddb/IDBObserver.h"
 
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/ExceptionStatePlaceholder.h"
 #include "bindings/modules/v8/ToV8ForModules.h"
 #include "bindings/modules/v8/V8BindingForModules.h"
@@ skipping 27 matching lines @@
         exceptionState.throwDOMException(TransactionInactiveError, IDBDatabase::transactionInactiveErrorMessage);
         return;
     }
     if (!database->backend()) {
         exceptionState.throwDOMException(InvalidStateError, IDBDatabase::databaseClosedErrorMessage);
         return;
     }
     database->backend()->observe(this, transaction->id());
 }
 
+void IDBObserver::unobserve(IDBDatabase* database, ExceptionState& exceptionState)
+{
+    if (!database->backend()) {
+        exceptionState.throwDOMException(InvalidStateError, IDBDatabase::databaseClosedErrorMessage);
+        return;
+    }
+    database->backend()->unobserve(this);
+}
+
 DEFINE_TRACE(IDBObserver)
 {
     visitor->trace(m_callback);
 }
 
 } // namespace blink